How do microwaves help heat frozen food?

А

The waves filter ice from food.

B

The waves block coldness in food.

с

The waves kill germs in food.

D

The waves are absorbed by water in food.

Answer:

Law 2:

Pushing a baby on a swing is easier than pushing an adult on the same swing. Water spills from a glass carried by someone who is walking steadily and suddenly stops short.

Law 2:

When thrown with the same force, a soccer ball accelerates more than a bowling ball.

Law 1:

A magician pulls a tablecloth out from under a dish on a table without disturbing the dish.

Law 3:

A rocket launches into space, pushing fuel exhaust in one direction and the rocket in the opposite direction.

Law 1:

A book rests on top of a shelf and does not move until a student accidentally knocks it off.

Explanation:

Newton's laws of motion:

Law 1: Law of inertia

Law 2: Law of force (F = mass x acceleration)

Law 3: Law of Action & Reaction

The laws followed by the given situations are Newton's law of force, Law of inertia and Newton's third law.

Inertia is defined as the tendency of an object to continue its state of rest or motion.

Here,

Considering the situations given,

1. Pushing a baby on a swing is easier than pushing an adult on the same swing.

This is because, the mass of the baby is lesser than that of the adult. So, according to Newton's force equation,

Force, F = ma

Therefore to push a body with more mass, more force should be applied.

Another situation that follows this law from the given situations is:

When thrown with the same force, a soccer ball accelerates more than a bowling ball.

2. Water spills from a glass carried by someone who is walking steadily and suddenly stops short.

This is due to the inertia of the water in the glass. This can be explained by law of inertia.

Another situation that follows this law from the given situations is:

A magician pulls a tablecloth out from under a dish on a table without disturbing the dish.

A book rests on top of a shelf and does not move until a student accidentally knocks it off.

3. A rocket launches into space, pushing fuel exhaust in one direction and the rocket in the opposite direction.

This is according to Newton's third law of motion. The law of action and reaction.

Hence,

The laws followed by the given situations are Newton's law of force, Law of inertia and Newton's third law.

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Answer:

6

Explanation:

From the given question, since a total of 12 V was obtained from the battery which is made up of a number of cells with each producing 2.0 V.

Assuming that the cells have a very low internal resistance, then;

minimum number of electric cells in the car battery = \(\frac{total voltage from the cells}{individual voltage of the cells}\)

                                          = \(\frac{12}{2}\)

                                          = 6

Thus, the minimum number of electric cells in the car battery is 6.

This implies that the addition of 6 cells which has 2.0 V supply in the battery produces a total of 12 V. Provided that the cells have a very low internal resistance.

Answer:c

Explanation:

Answer:

c

Explanation:

The flow speed in the hose v1=  2.81 m/s. The flow speed in the nozzle v2= 63.8 m/s

Using the principle of conservation of mass, the mass flow rate in the hose must be equal to the mass flow rate in the nozzle. Thus, we can write:

ρ1A1v1 = ρ2A2v2

where ρ is the density of water, A is the cross-sectional area of the hose or nozzle, and v is the flow speed. Solving for v1 and v2:

v1 = (ρ2A2/A1) v2

v2 = (A1/A2) v1

We are given the diameter of the hose and nozzle, so we can calculate their respective areas:

A1 = π(0.1/2)^2 = 0.00785 m^2

A2 = π(0.021/2)^2 = 0.000346 m^2

The density of water at room temperature is about 1000 kg/m^3. Substituting these values into the equations above:

v1 = (ρ2A2/A1) v2 = (1000 kg/\(m^3\))(0.000346 \(m^2\)/0.00785 \(m^2\)) v2 = 4.38 v2

v2 = (A1/A2) v1 = (0.00785 \(m^2\)/0.000346 \(m^2\)) v1 = 22.7 v1

Now, using the given mass flow rate of 22 kg/s:

ρ1A1v1 = 22 kg/s

v1 = 22 kg/s / (ρ1A1) = 22 / (1000 kg/\(m^3\))(0.00785 \(m^2\)) = 2.81 m/s

Substituting this value into the equation for v2:

v2 = (A1/A2) v1 = (0.00785 \(m^2\)/0.000346 \(m^2\)) (2.81 m/s) = 63.8 m/s

Therefore, the flow speed in the hose is 2.81 m/s and the flow speed in the nozzle is 63.8 m/s.

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The ball's height from the ground is 2.85 feet

V = 0

u= 56 feet/ second

h =?

h =\(\frac{u^2}{2g}\) = \(\frac{56}{2*9.8}\) = 2.85 feet

The concept of motion under gravity

When an object moves, it is said to be in motion under gravity since gravity has an impact on the object’s vertical motion.

GRAVITY is the force that pulls things downward. In actuality, gravity pulls objects toward the Earth’s center.

Consequently, v=gt is the equation of motion.

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Answer:

1 m/s so number 2 is the right one

Explanation:

so when it is at rest it still has some of the left over energy so it would be at 1 m/s

Normally, materials are electrically neutral because there are equal numbers of positively charged particles and negatively charged particles, hence option D is correct.

Since there are exactly as many electrons in an atom as there are protons, the positive and negative charges "balance out," leaving atoms electrically neutral.

Neutrons are found in the nuclei of all atoms, with the exception of the majority of hydrogen atoms. Neutrons are electrically neutral, as opposed to electrically charged protons and electrons.

Therefore, due to having an equal number of positively charged particles and negatively charged particles materials are electrically neutral.

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Complete Question:

A student has been assigned to measure the density of an irregularly shaped piece of metal.

Which apparatus would be most appropriate to carry out this task?

Group of answer choices

A. ruler, balance

B. beaker, crucible

C. flask, Bunsen burner

D. graduated cylinder, balance

Answer:

D. graduated cylinder, balance

Explanation:

In this scenario, A student has been assigned to measure the density of an irregularly shaped piece of metal.

The apparatus which would be most appropriate to carry out this task is a graduated cylinder and balance.

A graduated cylinder can be defined as a measuring cylinder used for the measurement of the volume of an irregularly shaped piece of metal or liquids. It is typically marked with horizontal lines on its side as units of measurement for volume. The balance is then used to weigh the metals mass.

The angular velocity in rpm of the bowling ball is equal to 71.32 rpm.

Given the following data:

Mass = 5.6 kg

Diameter = 20 cm to m = 0.2 m

Angular momentum = 0.22 kgm2/s

Radius = Diameter/2 = 0.22/2 = 0.11 m

Answer:15

Explanation:

Answer:

The nucleus and all non-valence electrons.

Number of oxygen molecules in each breath is 2.9X10^21

Given that the volume of air inside a breath (V) = 6.0×10^−4 m^3

oxygen in fresh air = 20%

volume of oxygen in fresh air = 20/100 x 6.0×10^−4 = 1.2x10-4m^3

pressure in the lungs (P)=  1.0×10^5 pa

Temperature of air (T) =300K

Using ideal gas equation find the number of moles of oxygen

PV = nRT

Then n = 1.0×10^5 x  1.2x10-4 / 8.314 x 300 = 4.8x10-3mol

We know the number of molecules in 1 mol is 6.023x10^23

Then the number of molecules in 4.8x10-3mol of oxygen is =

4.8x10-3molx 6.023x10^23 = 2.9x10^21

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Answer:

Explanation:

Assuming the satellite is in a circular orbit, we can use the following equations to calculate its time period, velocity, and acceleration:

Time period (T): T = 2π√(a^3/GM), where a is the radius of the orbit, G is the gravitational constant, and M is the mass of the Earth.

Velocity (v): v = √(GM/a), where G is the gravitational constant, M is the mass of the Earth, and a is the radius of the orbit.

Acceleration (a): a = v^2/a, where v is the velocity and a is the radius of the orbit.

Using the given radius of the orbit (a = 49870 km = 4.987 x 10^7 m) and the known values of G and M, we can calculate the time period, velocity, and acceleration as follows:

Time period: T = 2π√(a^3/GM) = 2π√((4.987 x 10^7)^3/(6.674 x 10^-11 x 5.972 x 10^24)) = 85514 seconds.

Therefore, the time period of the satellite is approximately 23.75 hours (85514 seconds / 3600 seconds per hour).

Velocity: v = √(GM/a) = √((6.674 x 10^-11 x 5.972 x 10^24)/(4.987 x 10^7)) = 3074.4 m/s.

Therefore, the velocity of the satellite is approximately 3074.4 m/s.

Acceleration: a = v^2/a = (3074.4 m/s)^2/4.987 x 10^7 m = 0.190 m/s^2.

Therefore, the acceleration of the satellite is approximately 0.190 m/s^2.

The change in velocity of the baseball is 39.72 m/s

This is the difference between the final and the initial velocity of a body.

To calculate the change in velocity of the ball, we use the formula below.

Where:

Make Δv the subject of the equation

From the question,

Given:

Substitute these values into equation 2

Hence, The change in velocity of the baseball is 39.72 m/s

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Answer:

5.0 m along the floor

Explanation:

i just learned that today

Answer:

magnetic energy (proton) and magnetic plasma.

Explanation:

Light propogates from soda lime glass into pyrex glass of different refractive indices indicating a change in the medium which can be used to find out the critical angle.

The critical angle is the angle of incidence for which the angle of refraction comes out to be 90°. It is related to the refractive indices (Plural of refractive index) by the following relation:

Sini = 1/u, where u is the ratio of refractive index of medium 2 and medium 1

According to the question, Light propogates from soda lime glass (Medium 1, u1=1.518) into pyrex glass(Medium 2, u2=1.473), i.e. from a denser medium to rarer medium. So, the ratio of refractive index becomes u2/u1= 1.473/1.518=0.97

Putting the ratio in the above-mentioned formula,

∴ Sini = 1/0.97

i= 75.9°

Hence, the critical angle(i) for the given situation is 75.9°.

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a..... 1.04 x 10⁻⁴ Vi

b.... 9500 V

A) Determine the capacitance (to the nearest 10 μF).

First, we should identify the formula that we will use to solve the problem.

The formula that relates to capacitance is:

C = 2E / V². Where C is the capacitance in farads, E is the energy stored in joules, and V is the voltage across the capacitor in volts.

Converting the energy to joules, we have: E = 250J.

Now we know that the voltage needs to drop to half of its initial value in 10 ms. We can use the following formula to calculate the capacitance: C = R x t / ln(Vi / Vf) where R is the resistance in ohms, t is the time in seconds, Vi is the initial voltage, and Vf is the final voltage, which is half of the initial voltage.

B) Plugging in the given values, we get:

C = 48 x 0.01 / ln(Vi / (Vi / 2))Simplifying and solving for capacitance, we get:

C = 1.04 x 10⁻⁴ ViNow we can use the energy formula to solve for Vi:Vi = √(2E / C)

Plugging in the given values, we get:Vi = √(2 x 250 / 1.04 x 10⁻⁴)Simplifying and solving for Vi, we get:Vi = 9469 V

Therefore, the capacitance that meets these specifications is 100 μF and the initial capacitor voltage that meets these specifications is 9500 V, to the nearest 100 V.

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a. Contact forces, friction, air resistance

Answer:

m=4kg

Explanation:

F=32, m=?, a=8ms^-2

F=ma

32=8m

32/8=m

m=4kg

Answer:

98ms^2

Explanation:

v^2=v1^2+2ad

a^2=(28m/s)^2 +2×a×4.00m

-784=8a

a=98m/s^2

The acceleration of the  diver as she travels through the water ​is - 98 m/s², negative sigh indicates that her speed is deceasing.

Acceleration is rate of change of velocity with time. Due to having both direction and magnitude, it is a vector quantity. Si unit of acceleration is meter/second² (m/s²).

Given parameters:

Initial speed of the board: u = 28 meters per second.

Final speed of the board: v = 0 meters per second.

Distance travelled: s = 4.0 meter.

Let the acceleration of the diver is = a.

Now, from v² = u² + 2as, it can be written that:

0² = 28² + 2a×4

a = - 28²/(2×4)

= - 98 m/s²

Hence, acceleration of the  diver as she travels through the water ​is - 98 m/s², negative sigh indicates that her speed is deceasing.

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Answer:

B) Make the ramp longer

Explanation:

A machine is a device that makes work more easier and faster. A machine also saves time.

A ramp is a simple machine that is used to lift heavy object with a force that is lesser than the actually force needed. A ramp is in the shape of an inclined plane, which makes pushing an object easier than the required force needed.

The formula for a ramp is given by:

Force needed to push * length of the ramp = weight of object * height of ramp.

Force needed to push = (weight of object * height of ramp) / length of ramp

We can see that the force needed is inversely proportional to the ramp length. Hence for a ramp with longer length you need lesser force to raise the object.

Answer:

a1)gravity

not sure on others

Explanation:

cause the gravity force pulls u down

Answer:

a) i) Gravitational force

ii) Air resistance

b) (I cannot understand what is the question saying but the unit of acceleration is m/\(s^{2}\) or \(ms^{-2}\))

ii) Because when the parachutist is falling, the gravitational force is pulling him down. But the air resistance is pushing him upwards acting against the gravitational force resulting in a decreasing acceleration.

iii) This is because soon the air resistance catches up with that of the gravitational force and it cancels the gravitational force so he is falling in a constant velocity. This is called terminal velocity when the gravitational force gets cancelled resulting in a free fall where his weight brings him down.

The radius of the satellite's motion is 2.49 × 10⁷ m

Since the centripetal force, F = mv²/r equals the gravitational force, F' = GMm/r² on the satellite,

F = F'

mv²/r = GMm/r²

v² = GM/r

Making r subject of the formula, we have

r = GM/v² where r = radius of satellite's motion, G = universal gravitational constant = 6.67 × 10⁻¹¹ Nm²/kg², M = mass of earth = 5.972 × 10²⁴ kg and v = speed of satellite = 4,000 m/s.

Substituting the values of the variables into the equation, we have

r = GM/v²

r = 6.67 × 10⁻¹¹ Nm²/kg² × 5.972 × 10²⁴ kg/(4,000 m/s)²

r = 39.83324 × 10¹³ Nm²/kg ÷ 16 × 10⁶ m²/s²

r = 2.4895775 × 10⁷ m

r ≅ 2.49 × 10⁷ m

So, the radius of the satellite's motion is 2.49 × 10⁷ m.

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Answer:

25.0 million meters

Explanation:

Answer:

260 km/h

Explanation:

Motion is said to be relative when the motion observed by the observer depends on the location (frame) of the observer.

When two objects are moving in opposite directions, the relative motion is obtained by subtraction.

Hence  the plane is moving at (285 - 25) km/h giving 260 km/h

Answer:

A physical property of matter is electric charge. It is caused by an imbalance in the number of protons and electrons in a material. Whether there are more protons than electrons in a substance, it is positively charged if there are more electrons than protons, it is negatively charged.

Explanation:

Answer:

Approximately \(2.8\; {\rm m\cdot s^{-1}}\).

Explanation:

If an object of mass \(m\) is travelling at a velocity of \(v\), the momentum \(p\) of that object would be \(p = m\, v\).

Momentum before collision:

Total momentum before collision:

Momentum after collision:

Momentum is conserved immediately before and after collisions. Hence, the total momentum of the two masses after the collision would be equal to the sum of their momentum before the collision, \(54\; {\rm kg \cdot m\cdot s^{-1}}\).

Subtract the momentum of the \(4.5\; {\rm kg}\) mass after the collision from the sum of momentum after the collision: \(54\; {\rm kg \cdot m\cdot s^{-1}} - 36\; {\rm kg \cdot m \cdot s^{-1}} = 18\; {\rm kg \cdot m \cdot s^{-1}}\).

Hence, the momentum of the \(6.5\; {\rm kg}\) mass after the collision would be \(18\; {\rm kg \cdot m \cdot s^{-1}}\). The velocity of this mass would be:

\(\begin{aligned}v &= \frac{p}{m} \\ &= \frac{18\; {\rm kg\cdot m \cdot s^{-1}}}{6.5\; {\rm kg}} \approx 2.8\; {\rm m\cdot s^{-1}}\end{aligned}\).

The solid cylinder's ultimate linear velocity is roughly 6.57 m/s.

We may use the concept of conservation of energy to calculate the final linear velocity of the solid cylinder. The system's initial potential energy is turned into the solid cylinder's ultimate kinetic energy.

Let us indicate the mass of the cylindrical shell and solid cylinder as m, the radius as R, the inclined plane's height as h, and the solid cylinder's ultimate linear velocity as v.

The potential energy at the inclined plane's top is provided by the formula:

Potential energy equals m * g * h.

where g is gravity's acceleration. Because they have the same mass and height, the potential energy for the cylindrical shell and solid cylinder is the same in this example.

The solid cylinder's kinetic energy is provided by the formula:

(1/2) * m * \(v^2\) = kinetic energy

The cylindrical shell has a larger moment of inertia than the solid cylinder since it is a hollow cylinder. This means that the solid cylinder will have a larger linear velocity for the same kinetic energy.

Adding potential energy to kinetic energy:

m * g * h = (1/2) * m * \(v^2\)

Simplifying the equation:

g * h = (1/2) *\(v^2\)

Now we can solve for v:

\(v^2\) = 2 * g * h

v = √(2 * g * h)

Plugging in the values:

v = √(2 * 9.8 * 2.2)

v ≈ √(43.12)

v ≈ 6.57 m/s

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The rock will take 3.61 seconds to hit the surface of the water.

The equations of motion can be described as the equation that described the relationship between the velocity (v & u), acceleration, time, and displacement (S) of a moving body.

The mathematical  expression of the equations of motion:

\(v = u +at\\S = ut +(1/2)at^2\\v^2-u^2 = 2aS\)

Given, the height of the bridge from the ground, h = 64.0 m

The gravitational acceleration on the rock, g = 9.8 m/s²

The initial speed of the rock, u = 0

From the 2nd equation of motion, calculate the time rock takes to hit the surface of the water:

h = ut + (1/2)gt²

64.0 = 0×t + (1/2)× 9.8×t²

t² = 64 ×2/9.8

t = 3.61 s

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