Question:

An object with a mass of 5.00 kg slides on an ideal frictionless surface. The object is pulled with a constant horizontal force of 10.0 N as shown below. What is the resulting acceleration?

Answer:

We can most easily get our results by again working in components (x and y). What we need to do is to write down all force components in x- and in y-direction separately.

y:	$\sum$Fy = N - mg = 0	=> N = m g
x:	$\sum$Fx = F = m ax = m a	=> a = F/m = (10.0 N)/(5.00 kg) => a = 2.00 m/s2

Thus what we find is that the acceleration is 2.00 m/s² in x-direction.

There are two important lessons to be learned here:

1. If the object remains on the surface, the normal force is always just big enough to balance all other forces in its direction.
2. Any unbalanced force in a given direction causes an acceleration in that direction.

© MultiMedia Physics, 1999