A 1600kg car is traveling over a hill that has a radius of curvature of 25m. The car is slowing down as it goes over the hill. It slows down at a constant rate from a speed of 25 m/s to a speed of 10 m/s over a distance of 50 m ending at the top of the hill. The net acceleration of the car at the top of the hill is most nearly

• 4.0 $\frac{m}{s^2}$

• 5.3 $\frac{m}{s^2}$

• 6.6 $\frac{m}{s^2}$

• 9.3 $\frac{m}{s^2}$

• 26 $\frac{m}{s^2}$

Tags

NGSS.HS-PS2-1

Blocks A and B have masses M and 2M, respectively. The blocks are connected using a light string and an ideal pulley in the Atwood machine shown. When the blocks are released from rest, block B accelerates downward with acceleration a. Block B is replaced with a block that has twice the mass. The blocks are again released from rest. Which of the following is a correct expression for the new acceleration of the blocks?

• $\frac{1}{3}a$

• $\frac{5}{9}a$

• $\frac{3}{5\ }a$

• $\frac{9}{5}a$

• $2a$

Tags

NGSS.HS-PS2-1

A block of mass m is sliding down an inclined plane that makes an angle θ with the horizontal, as shown in the figure. The coefficient of kinetic friction between the surface and the block is μ . Which of the following is a correct expression for the acceleration a of the block?

• $g(1-μ\cosθ)$

• $g(\sinθ−μ\cosθ)$

• $g(1+μ\cosθ)$

• $g(\sinθ+μ\cosθ)$

• $g(\sinθ−\cosθ)$

Tags

NGSS.HS-PS2-1

Blocks A and B of equal mass are on a horizontal surface and are connected by a light string. The blocks are pulled to the right by a horizontal force of magnitude F exerted on block B, as shown in the figure. There is negligible friction between the blocks and the horizontal surface. The blocks are accelerating to the right along the surface. Which of the following figures accurately represents the magnitudes and directions of the horizontal forces on the blocks?

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Tags

NGSS.HS-PS2-1

A 650 kg car moving to the right at 20 m/s collides with a stationary 2250 kg truck. Which of the following graphs could represent the force as a function of time for both the car and the truck during the collision?

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Tags

NGSS.HS-PS2-1

NGSS.HS-PS2-2

A cart of mass M is approaching a hill with a circular top of radius R, as shown in the figure above. The cart is carrying a load also of mass M and is traveling with speed v₀ when it is at the top of the hill. The length of the cart is negligible in comparison to the radius of the hill. The cart never loses contact with the hill’s surface. The cart and load can both be considered to be at the same position.

Which of the following claims identifies an action-reaction pair of forces due to Newton’s third law and provides appropriate reasoning to justify this claim?

• The normal force exerted on the load by the cart and the gravitational force exerted on the load by Earth, because these are equal and opposite forces that act on the same object.

• The normal force exerted on the load by the cart and the gravitational force exerted on the load by Earth, because these are equal and opposite forces that act on different objects.

• The normal force exerted on the load by the cart and the normal force exerted on the cart by the load, because these are equal and opposite forces that act on the same object.

• The normal force exerted on the load by the cart and the normal force exerted on the cart by the load, because these are equal and opposite forces that act on different objects.

• The gravitational force exerted on the cart by Earth and the normal force exerted by the hill on the cart, because these are equal and opposite forces that act on different objects.

A cart of mass M is approaching a hill with a circular top of radius R, as shown in the figure above. The cart is carrying a load also of mass M and is traveling with speed v₀ when it is at the top of the hill. The length of the cart is negligible in comparison to the radius of the hill. The cart never loses contact with the hill’s surface. The cart and load can both be considered to be at the same position.

The speed v_min is the minimum speed necessary for the cart and the load to leave the surface of the hill at the top of the hill. If the load is removed, what is the new minimum speed necessary for the cart to leave the surface of the hill?

• $\frac{1}{4}\ v_{\min}$

• $\frac{1}{2}\ v_{\min}$

• $v_{\min}$

• $2\ v_{\min}$

• $4\ v_{\min}$

Tags

NGSS.HS-PS2-1

A cart of mass M is approaching a hill with a circular top of radius R, as shown in the figure above. The cart is carrying a load also of mass M and is traveling with speed v₀ when it is at the top of the hill. The length of the cart is negligible in comparison to the radius of the hill. The cart never loses contact with the hill’s surface. The cart and load can both be considered to be at the same position.

In a free-body diagram showing all the forces (and not components) acting on objects at the top of the hill, how many vertical forces will act on the cart, and how many vertical forces will act on the load?

• Cart: 2; Load: 2

• Cart: 2; Load: 3

• Cart: 3; Load: 2

• Cart: 3; Load: 3

• Cart: 4; Load: 3

Tags

NGSS.HS-PS2-1

NGSS.HS-PS2-4

An Atwood's machine consists of two blocks connected by a light string that passes over a set of ideal pulleys, as shown above. Blocks A and B have masses 1/2 M and M , respectively. The blocks are released from rest and block B moves downward with an acceleration of magnitude a. Next, a block of mass 1/4 M is attached to block A , and the system is again released from rest. Which of the following gives the change in acceleration of block B ?

• A decrease of $\frac{1}{3\ }g$

• A decrease of $\frac{1}{7\ }g$

• An increase of $\frac{1}{7\ }g$

• A decrease of $\frac{4}{21\ }g$

• An increase of $\frac{4}{21\ }g$

Tags

NGSS.HS-PS2-1

Blocks A and B of masses m_A and m_B, respectively, are attached to an ideal pulley to create the Atwood’s machine shown in the figure. Which of the following free-body diagrams could be correct for the blocks when they are released from rest if m_B>m_A?

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Tags

NGSS.HS-PS2-1