Physics Quiz

A block, initially at rest on a horizontal track, is compressed against a spring as shown in Figure 1. The block is released from rest, slides across the horizontal track and then up a curved ramp, as shown in Figure 2. Frictional forces are negligible. The block momentarily comes to rest near the top of the ramp. Consider the block, spring, and Earth as a single system. Which of the following explains why the block comes to rest while on the ramp?

• All the mechanical energy in the system has been dissipated.

• All the mechanical energy in the system has been transferred into the block’s motion.

• All the mechanical energy in the system has been lost to thermal energy.

• All mechanical energy in the system is now in the form of gravitational potential energy.

Tags

NGSS.MS-PS3-2

NGSS.MS-PS3-5

A sphere of mass m is thrown horizontally with a speed v₀ from an initial height h₀ above the ground. The sphere eventually lands on the ground. Which of the following expressions is equal to the speed of the sphere at the instant the sphere is a distance h₀/2 above the ground?

• √(gh₀)

• √(2gh₀)

• √(v₀² + 2gh₀)

• √(v₀² + gh₀)

Tags

NGSS.HS-PS3-1

NGSS.HS-PS3-2

A rock with mass 2 kg is dropped from the top of a building and falls straight down. The graph shows the vertical position of the rock as a function of time. From time t = 0 to t = t₁, the force of air resistance does -80 J of work on the rock. Which of the following is most nearly the change in kinetic energy of the rock from time t = 0 to t = t₁?

• 520 J

• 600 J

• 720 J

• 800 J

Tags

NGSS.HS-PS2-1

NGSS.HS-PS3-1

An object slides down an incline where there is friction between the object and incline, but negligible air resistance. Which of the following must be true about the resulting changes in the kinetic energy of the object and the gravitational potential energy of the object-Earth system?

• The sum of the kinetic energy and the gravitational potential energy changes by an amount equal to the energy dissipated by friction.

• The gravitational potential energy decreases and the kinetic energy is constant.

• The decrease in the gravitational potential energy is equal to the increase in kinetic energy.

• The gravitational potential energy and the kinetic energy must both decrease.

Tags

NGSS.HS-PS3-1

A student takes an object to the top of a very tall cliff and throws the object off the cliff either straight up or straight down. The graph represents the kinetic energy of the object as a function of time. Based on the graph, which of the following correctly indicates whether the student threw the object up or down and provides a correct justification for that conclusion?

• The object was thrown straight up. The kinetic energy is always positive.

• The object was thrown straight up. The kinetic energy decreases, then increases.

• The object was thrown straight down. Kinetic energy is always positive.

• The object was thrown straight down. The kinetic energy decreases, then increases.

Tags

NGSS.HS-PS3-2

The graphs show the magnitude F of the force exerted on an object as a function of the object’s position x for two trials in an experiment. The force F is exerted in the direction of motion for both trials. W₁ and W₂ are the work done on the object by Force 1 and Force 2, respectively, as the object moves from x = 0 to x = 1.0 m. How do W₁ and W₂ compare, and why?

• W₁ < W₂, because the area under the curve of Force 1 over the region 0 < x < 1 m is smaller than the area under the curve of Force 2 over the same region.

• W₁ < W₂, because at the midpoint, x = 0.5 m, the value of Force 1 is less than the value of Force 2.

• W₁ > W₂, because the maximum value of Force 1 is greater than the maximum value of Force 2.

• W₁ > W₂, because the slope of Force 1’s graph increases, while the slope of Force 2’s graph decreases.

Tags

NGSS.HS-PS2-1

A 2.0 kg object can move on a straight, horizontal track with negligible friction. The object is initially at rest at position x = 0, when a horizontal force is exerted on the object. The force is measured as a function of the object’s position, and the data are shown in the graph. What is the speed of the object when the object is at position x = 2.0 m?

• 2.8 m/s

• 4.0 m/s

• 5.7 m/s

• 8.0 m/s

Tags

NGSS.HS-PS2-1