physics
posted by pinky .
i need help i don't understand how to do this problem so please help me.
A student lifts a 5kg chair 0.8m off the floor, walks at a constant speed for a distance 10m, and then puts the chair back down on the floor. calculate the total amount of work done on the chair.

total work done: zero. He lifted the chair, and put it back down.
In the first, he did work against gravity. Then walking, he did no work. At the end, gravity did work on the chair: total: zero