Ok anybody please help me with this question in which situation below which do N

ID: 2120678 • Letter: O

Question

Ok anybody please help me with this question in which situation below which do NOT do work. Thanks a million

1)Gravity acting on a ball rolling across a table.

2)Gravity acting on a ball falling off a table.

3)Friction acting on a ball rolling across a table.

4)Friction acting on a hockey puck sliding across a table.

5)The coil springs supporting a car which is staionary.

6)The coil springs supporting a car which is moving over a smooth road.

7)The spring which, when released, launches a pin ball.

8)The twisted rubber band which is turning the propeller on a small model airplane, which is being held stationary in the hand of the operator.

1)Gravity acting on a ball rolling across a table.

2)Gravity acting on a ball falling off a table.

3)Friction acting on a ball rolling across a table.

4)Friction acting on a hockey puck sliding across a table.

5)The coil springs supporting a car which is staionary.

6)The coil springs supporting a car which is moving over a smooth road.

7)The spring which, when released, launches a pin ball.

8)The twisted rubber band which is turning the propeller on a small model airplane, which is being held stationary in the hand of the operator.

as we know work = dot product of force and distance traveled.

so work = Fdcos(theta) where theta is angle between

if angle between force and distance is 90 than work 0.

1) no work as there is nochange in vertical length. Ball is rolling in horizonatal.(as theta 90)

2) there will be work as there change in vertical length.(W = fd as theta 0)

3)here theta will be 180 so there will be work =Fd;

4)yes there will be work.

5)there is no work currently but when spring will be compressed then there will be.

6)on a smooth road there will not be compression in spring so no work.

7)there will be work as there is change in spring which require some work to do this..

8)here also will be no work done explanation same as the spring.

so there willl be no work in case of

1 , 5,6,8

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