Why a body moving in a straight line with constant velocity has a resultant force of 0?
ii) moving in a straight line with constant velocity There is no reason to say straight line with constant velocity. Just say constant velocity – that is enough because constant velocity means in a straight line with constant speed. You may say ii)moving with constant velocity Or you may say ii)moving in a straight line with constant speed Both mean the same. Now let us come to your example. Suppose the block is at rest. You apply 5 N force to the right. There is resistance of 5N. There is no other (i.e. third) unbalanced force on the block. Then the block will not move. It will remain at rest. Suppose the block is moving. You apply 5 N force towards right. There is resistance of 5 N. There is no other (i.e. third) unbalanced force. The block will continue to move in a straight line with constant speed. What will be the direction? The direction will be same as the direction in which it was earlier moving. Note: Do not think that just because you apply force to right, it will start movi
