# Second law of motion

1. Nov 19, 2007

### udar subedi

in the newtons second law of motion we study "F=ma" letters having their usual meanings.
so if any object say"A" comes in the way of a huge object "B", moving with a constant velocity; a=0, doesnt the object "a" feel any force upon him?

2. Nov 19, 2007

### CompuChip

When two objects collide, they are in contact for a while. At that time they exert a force on one another and they will accelerate (that is, one will decelerate and the other will accelerate, so in the end the moving one will go slower and the stationary one will be moving = going faster). The amount of time for which they are in contact is usually very short though. Also, we hardly ever need to know exactly how long it is, as problems involving colliding objects can usually be solved by looking at the (kinetic) energies before and after the collision.

3. Nov 19, 2007

### stewartcs

Object A will feel an effective force which is approximately equal to m*v/t

where,

m = mass of object B
v = velocity of object B
t = time of contact

4. Nov 21, 2007