1). A machine lifts a ball 10.0 meters into the air and then lowers it back to t
ID: 1880623 • Letter: 1
Question
1). A machine lifts a ball 10.0 meters into the air and then lowers it back to the ground. A person pushes her trunk 10.0 m down the hallway and then pushes it back to the same location. In which case is the total work done on the object equal to zero?
A). Both, because they travelled the same distances and returned to their starting location.
B). The ball, because gravity is a conservative force
C). The trunk, because friction is a non-conservative force.
D). More information about the object's masses is needed.
2). It is not possible for an object's kinetic energy to be less than zero, but it is possible for an object's gravitational potential energy to be negative. Why?
A). Potential energy has to do with distances, and distance can be negative.
B). The location where the object has zero potential energy is arbitrary and can be moved around.
C). It often balances the object's kinetic energy.
D). Gravity always points down, and this is the negative direction.
A). Both, because they travelled the same distances and returned to their starting location.
B). The ball, because gravity is a conservative force
C). The trunk, because friction is a non-conservative force.
D). More information about the object's masses is needed.
2). It is not possible for an object's kinetic energy to be less than zero, but it is possible for an object's gravitational potential energy to be negative. Why?
A). Potential energy has to do with distances, and distance can be negative.
B). The location where the object has zero potential energy is arbitrary and can be moved around.
C). It often balances the object's kinetic energy.
D). Gravity always points down, and this is the negative direction.
Explanation / Answer
(1) correct option is A.
Because the net displacement is ZERO as they returned to its original position
(B) Correct option is B.
Gravitational potential energy is always measured with some reference point if we move it can vary.
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