Energy Unit Quiz

Energy...

• is a quantity that can be stored

• can be related to motion

• can be related to position

• all of these

Dislplayed are the energy diagrams for an object for both before and after an external agent has acted on the system. The amount of work done on the system is?

• 3 J

• is equal to the difference in mechanical energy

• cannot be determined

• is always positive

A projectile is fired with the same initial speed at two different angles. The trajectories are shown. Which statement below is true regarding the intersection (black dot). Ignore the effects of drag.

• both points have the same kinetic energy

• both points have the same potential energy

• both points would have the same energy diagrams

• all of the above

Displayed is a force vs displacement diagram for an object. What is the object's change in kinetic energy?

• At zero or close to 0 J

• Much greater than 0 J

• cannot be determined unless the initial speed is given

• it is positive then negative

You carry a box of weight 3 lbs (1 lb = 4.45 N ) up a horizontal ramp at a constant velocity. The ramp has a height of 7.0 m. The base of the ramp is 22.5 m. There is a drag force (F_D) caused by a gust of wind down the ramp that pushes down and parallel to the surface of the ramp with a constant force of 3.5 N. What is the net work done of the box?

• 131 J

• 2948 J

• 917 J

• 0 J

The same net force is applied to object A and object B over the same distance. Object A has a mass of 10 kg. Object B has a mass that is 20 kg. If object A has a change in kinetic energy of 3.0 J then

• object B also has a change in kinetic energy of 3.0 J

• object B has a change in kinetic energy less than 3.0 J because its mass is less.

• object B has a change in kinetic energy greater than 3.0 J because its mass is more

• not enough information

Shown is the potential energy function for a marble as it moves along the x-axis. Which locations correspond to a conservative force that is in the “+” x-direction?

• w

• x

• y

• z

True (a) or False (b). Frictional forces can never do positive work.

• a) True

• b) False

A particle moves under along the x axis under the influence of a stationary object. The force exerted on the particle is given by F = 8 x³ i, where F has units of Newtons and x is in meters. If x = 0 is taken to be the zero of potential energy, then the potential energy in joules is given by:

• 2x⁴

• -2x⁴

• 24x²

• -24x²

An elevator lifts a max load of 15,000 N at a speed of 3.0 m/s. What is the power rating of the elevator?

• 5.0 W

• 45,000 J

• 45, 000 J/s

• 5,000 J/s