Question 21 (1 point)
Wnet = ΔEk = Ek,f − Ek,i
When a net force does work on an object, then there is always a change in
Question 21 options:
distance.
position.
net forces acting on the object.
kinetic energy.
Question 22 (1 point)
How much work is done if a machine exerts 850 watts of power in 30 seconds?
Question 22 options:
25,500J
2550J
28.3J
283J
Question 23 (1 point)
A battery is connected to a motor. The battery releases enough energy to perform 200 J of work, but the motor produces only 90 J. Why?
Question 23 options:
The motor is connected to the battery in parallel.
The motor is connected improperly.
Some energy is released as heat.
The battery has a leak.
Question 24 (1 point)
Wnet = ΔEk = Ek,f − Ek,i
A 1 kg brick is dropped from a height of 10 m. Calculate the work that has been done on the brick between the moment it is released and the moment when it hits the ground. Neglect air resistance.
Question 24 options:
0 J
98 J
196 J
49 J
Question 25 (1 point)
A brick has a mass of 300 g. This brick is dropped from a height of 20 m. What is the work done on the brick by gravity when it reaches the halfway mark?
Question 25 options:
29.4 J
58.8 J
14.9 J
117.6 J
Question 28 (1 point)
You pull into a gas station and fill up your car with gasoline. During the time you are filling up, the car has
Question 28 options:
neither potential or kinetic energy.
potential energy only.
both potential and kinetic energy.
kinetic energy only.
Question 29 (1 point)
K=1/2m*v^2
Kinetic energy is mass times velocity squared.
U=mgh
Potential energy is mass times acceleration of gravity time height.
A dynamic cart is pushed up an inclined plane with a speed, V. It reaches a height, h. If the initial speed were doubled, then what height would the cart reach?
Question 29 options:
Speed and height have no clear relationship.
4h
Less than 2h
2h
Question 31 (1 point)
A cue ball with mass 170 g hits the stationary number 8 ball, which has mass 160 g. The cue ball and the 8 ball move with a speed of 0.2 m/s and 0.3 m/s respectively after the collision. What was the speed of the cue ball before the collision?
Question 31 options:
0.2502 m/s
0.5319 m/s
0.4823 m/s
0.5008 m/s
Question 36 (1 point)
The winter sport of curling involves sliding a large granite stone on ice with the objective of placing it closest to the center of the ring. The curler causes the path of the stone to curve by giving it an initial circular rotation. Sweepers use brooms to sweep the path in front of the stone. How does the motion of the sweepers relate to the conservation of angular momentum?
Question 36 options:
The sweepers minimize friction between the stone and ice which helps maintain the angular momentum.
The sweepers motion creates circular air motion which adds to the angular momentum.
The sweepers motion adds torque to the stone's angular momentum.
The sweepers create circular patterns in the ice to increase the angular momentum.
