QUESTION FOR THE DAY

1. A child who is 7 years old, lifts a 40 kg-bag from the floor onto a table that is 3-feet high from the floor. If an adult, who is 25 years old lifts the same bag from the floor onto the same table, who do you think has done more work?

A. The child

B. The adult

C. Both did the same amount of work

D. No work is done

2. A child who is 7 years old, lifts a 40 kg-bag from the floor onto a table that is 3-feet high from the floor. If an adult, who is 25 years old lifts the same bag from the floor onto the same table, who do you think put in more energy?

A. The child

B. The adult

C. Both did the same amount of work

D. No work is done

ANSWERS

Work is defined as the force times the distance through which it acts.

Work = Force x Distance

1. C The force is derived from the mass of the bag which is its weight. Remember F = mg. That is, Force = mass x acceleration due to gravity. Since they lift the same weight through the same distance of 3 feet onto the table, the work done by both of them is the same.  

2. A The work done is the same but the child puts in more energy to do the same amount of work. Energy is the ability to do work.