AP Physics Dynamics - Newton's 2nd Law Problems

Two blocks are pushed along a horizontal frictionless surface by a force of 20 newtons to the right, as shown above. The force that the 2-kilogram block exerts on the 3-kilogram block is

• 8 newtons to the left

• 8 newtons to the right 

• 10 newtons to the left

• 12 newtons to the right

• 20 newtons to the left

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NGSS.HS-PS2-1

Three blocks of masses 3m, 2m, ands are connected to strings A, B, and C as shown above. The blocks are pulled along a rough surface by a force of magnitude F exerted by string C. The coefficient of friction between each block and the surface is the same. Which string must be the strongest in order not to break?

• A

• B

• C

• They must all be the same strength.

• It is impossible to determine without knowing the coefficient of friction.

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NGSS.HS-PS2-1

A block moving to the right on a level surface with friction is pulled by an increasing horizontal force also directed to the right. As the applied force increases, which of the following is true of the normal force and the frictional force on the block?

• A

• B

• C

• D

• E

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NGSS.HS-PS2-1

A homeowner pushes a lawn mower across a horizontal patch of grass with a constant speed by applying a force P. The arrows in the diagram correctly indicate the directions but not necessarily the magnitudes of the various forces on the lawn mower. Which of the following relations among the various force magnitudes, W, f, N, P is correct?

• P > f and N > W

• P < f and N = W

• P > f and N < W

• P = f and N > W

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NGSS.HS-PS2-1

Two blocks of mass 1.0 kg and 3.0 kg are connected by a string which has a tension of 2.0 N. A force F acts in the direction shown to the right. Assuming friction is negligible, what is the value of F?

• 2 N

• 4 N

• 6 N

• 8 N

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NGSS.HS-PS2-1

The 10.0 kg box shown in the figure to the right is sliding to the right along the floor. A horizontal force of 10.0 N is being applied to the right. The coefficient of kinetic friction between the box and the floor is 0.20. The box is moving with:

• acceleration to the left.

• acceleration to the right.

• constant speed and constant velocity.

• constant speed but not constant velocity.

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NGSS.HS-PS2-1

Three objects can only move along a straight, level path. The graphs below show the position d of each of the objects plotted as a function of time t.The sum of the forces on the object is zero in which of the cases?

• II only

• III only

• I and II only

• I and III only

• I, II, and III

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NGSS.HS-PS2-1

NGSS.HS-PS2-2

If F₁ is the magnitude of the force exerted by the Earth on a satellite in orbit about the Earth and F₂ is the magnitude of the force exerted by the satellite on the Earth, then which of the following is true?

• F₁ is much greater than F₂.

• F₁ is slightly greater than F₂.

• F₁ is equal to F₂.

• F₂ is slightly greater than F₁

• F₂ is much greater than F₁

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NGSS.HS-PS2-1

NGSS.HS-ESS1-4

NGSS.HS-PS2-4

A 20 N block is being pushed across a horizontal table by an 18 N force. If the coefficient of kinetic friction between the block and the table is 0.4, find the acceleration of the block.

• 0.5 m/s²

• 1 m/s²

• 5 m/s²

• 7.5 m/s²

• 9 m/s²

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NGSS.HS-PS2-1

The cart of mass 10 kg shown above moves without frictional loss on a level table. A 10 N force pulls on the cart horizontally to the right. At the same time, a 30 N force at an angle of 60° above the horizontal pulls on the cart to the left. What is the magnitude of the horizontal acceleration of the cart?

• 0.5 m/s²

• 1.6 m/s²

• 2.0 m/s²

• 2.5 m/s²

• 2.6 m/s²

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NGSS.HS-PS2-1