Question 1 A pickup truck is driving down the road to the east with a box restin

Question

Question 1

A pickup truck is driving down the road to the east with a box resting in the bed in the back. If the truck is slowing down, the friction force on the box from the truck is acting in which direction?

a. East

b. West

c. Down

d. There is no friction force in this situation.

Question 2

Which of the following is not a force?

a. Weight

b. Gravity

c. Tension

d. Drag

Question 3

A heavy ball is thrown straight up into the air with an initial kinetic energy of 100 J. It is then caught at the same height from which it was thrown. Assuming there is some air resistance, how much kinetic energy will it have right before it is caught

b. A little less than 100 J

c. About 0 J

d. Significantly less than 100 J

Question 4

Which of the following is not true?

a. Energy is the universe is conserved.

b. Energy is created from nothing inside the sun

c. Energy is an abstract concept. We have no idea what it actually is.

d. A falling ball can be understood as a conversion from potential energy into kinetic energy

Explanation / Answer

1)

as the truck is slowing down ,

the acceleration of truck is towards west.

the frictional force acting from the truck is in

b. West

2)

Here,

weight is not a force but a mwasure of the force of gravoty acting on an object.

3)

initial kinetic enegry = 100 J

as there is no loss of mechanical energy

kinetic energy + potential energy = mechanical energy

change in kinetic energy + change in potential energy = 0

at the same height , change in potential energy = 0 J

hence , change in kinetic energy = 0 J

kinetic energy will have A.a little less than 100 J

4)

false statement is b. Energy is created from nothing inside the sun

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