you lift a chair that weighs 50 n to a height of 0.5cm and carry it 10 m across the room how much work do you do on the chair.
I just want to make sure is it 25J because you are only doing work if you are lifting it but walking with it isn't work because the direction of the objects motion isnt the same as the direction of force. Am I right?
I think you mean lift the chair .5m, in that case, work is 25J
Yes, you are correct. Work is defined as the product of the force applied on an object and the distance over which the force is applied, both in the same direction. In this scenario, there are two tasks: lifting the chair and carrying it.
When you lift the chair to a height of 0.5 cm, you are doing work against gravity. The work done in this case can be calculated using the formula:
Work = Force × Distance
The force is equal to the weight of the chair, which is given as 50 N. The distance is the height to which you lift the chair, which is 0.5 cm (or 0.005 m). Plugging these values into the formula, we get:
Work = 50 N × 0.005 m = 0.25 J
So, when you lift the chair, you are doing 0.25 joules of work against gravity.
However, while carrying the chair across the room, you are not doing any work on the chair. As you correctly mentioned, work is only done when the direction of force is the same as the direction of motion. In this case, although you are exerting a force to carry the chair, the direction of the force is horizontal (parallel to the direction of motion) and not vertical (against gravity). Therefore, the work done while walking with the chair is considered negligible.
Hence, the total work done on the chair in this scenario is 0.25 joules from lifting it up to a height of 0.5 cm.