Physics Quiz: Newtons Laws, Forces, FBDs

In a collision between a huge SUV and a small hybrid car, the SUV exerts a larger force on the hybrid than the hybrid exerts on the SUV.

• True

• False

Answer explanation

According to Newton's third law, for every action, there is an equal and opposite reaction. Therefore, the force exerted by the SUV on the hybrid is equal to the force exerted by the hybrid on the SUV, making the statement false.

A satellite is in orbit around the earth. Which one feels the greater force?

• the satellite because the earth is so much more massive

• the earth because the satellite has so little mass

• Earth and the satellite feel exactly the same force.

• It depends on the distance of the satellite from Earth.

Answer explanation

According to Newton's third law, the Earth and the satellite exert equal and opposite forces on each other. Therefore, both the Earth and the satellite feel exactly the same force, despite their mass difference.

Tags

NGSS.HS-PS2-1

NGSS.HS-PS2-4

You push on box G that is next to box H, causing both boxes to slide along the floor, as shown in the figure. The reaction force to your push is

• the push of box G on box H.

• the push of box H on box G.

• the push of box G against you.

• the upward force of the floor on box G.

Answer explanation

The correct reaction force to your push is the push of box G against you, as per Newton's third law. For every action, there is an equal and opposite reaction, meaning your push on box G results in a push back from it.

Tags

NGSS.HS-PS2-1

Two blocks, A and B, are being pulled to the right along a horizontal surface by a horizontal 100-N pull, as shown in the figure. Both of them are moving together at a constant velocity of 2.0 m/s to the right, and both weigh the same. Which of the choices below shows a correct free-body diagram of the horizontal forces acting on the upper block, A?

• A → 100N

• 100N ← A → 100N

• A ← 100N 100N

• A → 50N

• A (No horizontal forces act on A.)

Answer explanation

Since blocks A and B are moving at a constant velocity, the net horizontal force on block A is zero. Therefore, no horizontal forces act on A, making the correct choice: A (No horizontal forces act on A).

Tags

NGSS.HS-PS2-1

Which of the choices below shows a correct free-body diagram of the horizontal forces acting on the lower block, B?

• B → 100N

• 100N ← B → 100N

• B ← 100N 100N

• B → 50N

• B (No horizontal forces act on B.)

Answer explanation

The correct choice, '100N ← B → 100N', accurately represents the horizontal forces acting on block B, indicating that there are equal forces acting in opposite directions on the block. We know this is true because despite having a force applied to it, the box is not accelerating.

Tags

NGSS.HS-PS2-1

You are in a train traveling on a horizontal track and notice that a piece of luggage starts to slide directly toward the front of the train. From this observation, you can conclude that this train is

• speeding up.

• slowing down.

• changing direction.

• speeding up and changing direction.

• slowing down and changing direction.

Answer explanation

The luggage sliding toward the front indicates that the train is decelerating. In a train that is slowing down, objects inside will move forward relative to the train's frame of reference.

Tags

NGSS.HS-PS2-1

A net force of 125 N is applied to a certain object. As a result, the object accelerates with an acceleration of 24.0 m/s². The mass of the object is

• 3000 kg.

• 144 kg.

• 0.200 kg.

• 5.21 kg.

Answer explanation

Using Newton's second law, F = ma, we can find the mass. Rearranging gives m = F/a. Substituting the values, m = 125 N / 24.0 m/s² = 5.21 kg. Thus, the mass of the object is 5.21 kg.

Tags

NGSS.HS-PS2-1

What magnitude net force is required to accelerate a 1200-kg car uniformly from 0 m/s to 27.0 m/s in 10.0 s?

• 444 N

• 1620 N

• 3240 N

• 4360 N

• 11800 N

Answer explanation

To find the net force, use F = ma. First, calculate acceleration: a = (final velocity - initial velocity) / time = (27.0 m/s - 0 m/s) / 10.0 s = 2.7 m/s². Then, F = 1200 kg * 2.7 m/s² = 3240 N.

Tags

NGSS.HS-PS2-1

How much tension force must a rope withstand to accelerate a 1210 kg car at 1.20 m/s²? Ignore friction.

• 1452 N

• 1210 N

• 1008 N

• 2420 N

Answer explanation

To find the tension force, use F = ma. Here, F = 1210 kg * 1.20 m/s² = 1452 N. Thus, the rope must withstand a tension force of 1452 N to accelerate the car.

Tags

NGSS.HS-PS2-1

An object is moving with constant velocity. Which of the following statements about it must be true?

• A constant force is being applied to it in the direction of motion.

• No net force is acting on it.

• It is accelerating.

• It is slowing down.

Answer explanation

An object moving with constant velocity has no net force acting on it, according to Newton's first law. This means it is not accelerating or slowing down, and no constant force is applied in the direction of motion.

Tags

NGSS.HS-PS2-1