AP Physics Energy and Momentum

A bar is pivoted about one end and is initially at rest in a vertical position. The bar is displaced slightly and as it falls it makes an angle 𝜽 with the vertical at any given time. Which of the following graphs best represents the bar’s angular acceleration 𝜶 as a function of angle 𝜽 ?

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A stone falls from rest from the top of a building as shown above. Which of the following graphs best represents the stone’s angular momentum L about the point P as a function of time?

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A specially designed spring is stretched from equilibrium to the distances x given in the table above, and the restoring force F is measured and recorded in each case. What is the potential energy of the spring when it is stretched 3 m from equilibrium?

• 9/2 J

• 9 J

• 81/4 J

• 27 J

• 81/2 J

Tags

NGSS.HS-PS3-1

A conservative force has the potential energy function U ( x ), shown by the graph above. A particle moving in one dimension under the influence of this force has kinetic energy 1.0 joule when it is at position x₁. Which of the following is a correct statement about the motion of the particle?

• It oscillates with maximum position x₂ and minimum position x₀.

• It moves to the right of x₃ and does not return

• It moves to the left of x₀ and does not return

• It comes to rest at either x₀ or x₂

• It cannot reach either x₀ or x₂

The graph above shows the force on an object of mass M as a function of time. For the time interval 0 to 4 s, the total change in the momentum of the object is

• 40 kgm/s

• 20 kgm/s

• 0 kgm/s

• -20 kgm/s

• indeterminable unless the mass M of the object is known

Tags

NGSS.HS-PS2-1

The graph above shows the force acting on an object as a function of time. The change in momentum of the object from time 0 to t is

• 2Ft

• Ft

• 0.5 Ft

• 0.25 Ft

• zero

Tags

NGSS.HS-PS2-1

A disc of mass m slides with negligible friction along a flat surface with a velocity v. The disc strikes a wall head-on and bounces back in the opposite direction with a kinetic energy one-fourth of its initial kinetic energy. What is the final velocity of the disc?

• v/4

• v/2

• -v

• -v/2

• -v/4

Tags

NGSS.HS-PS2-2

A particle of mass m starts from rest at position x = 0 and time t = 0. It moves along the positive x-axis under the influence of a single force Fx = bt , where b is a constant. The velocity v of the particle is given by

• bt/m

• bt²/2m

• bt²/m

• b/mt

Tags

NGSS.HS-PS2-1

A student holds one end of a string in a fixed position. A ball of mass 0.2 kg attached to the other end of the string moves in a horizontal circle of radius 0.5 m with a constant speed of 5 m/s. How much work is done on the ball by the string during each revolution?

• 0 J

• 0.5 J

• 1.0 J

• 2*pi J

• 5*pi J

Tags

NGSS.HS-PS3-2

An object moving on a horizontal, frictionless surface makes a glancing collision with another object initially at rest on the surface. In this case which of the following is true about momentum and kinetic energy?

• Momentum is always conserved, and kinetic energy may be conserved

• Kinetic energy is always conserved, and momentum may be conserved.

• Momentum is always conserved, and kinetic energy is never conserved

• Both momentum and kinetic energy are always conserved

• Neither momentum nor kinetic energy is conserved

Tags

NGSS.HS-PS2-2