Question

Which of the following is not true?
A crate sliding across the floor does work against frictional forces
Work is done if a component a force acting on an object exists in the direction of its displacement
A man with a bag of cement on his head does work to move the bag of cement as he walks from place to place on a
flat horizontal floor
Work is a scalar quantity

Answer 1

51061, Physics, Mechanics — Kinematics — Dynamics

Question Which of the following is not true?

A crate sliding across the floor does work against frictional forces;

Work is done if a component a force acting on an object exists in the direction of its displacement;

A man with a bag of cement on his head does work to move the bag of cement as he walks from place to place on a flat horizontal floor;

Work is a scalar quantity.

Solution The following is not true:

A man with a bag of cement on his head does work to move the bag of cement as he walks from place to place on a flat horizontal floor.

This is not true, as while moving the bag, the man does not act with a force along the direction of movement. Hence, work is 0 as the force is 0.

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