Calculating frictional force?

Question

How can i calculate the frictional force of a suface when i only know the deceleration of an object i rolled along it?

Answer 1

F = m*a  would give you the frictional force

So you would also need to know the mass or some other information.

Answer 2

There is negative acceleration.

Friction = -ma

m = mass

a = acceleration

a is negative. In the formula F = -ma, a minus sign is used. So, friction becomes positive.

You should use this formula only if friction is the only force causing change in velocity. If some other force is also responsible, then this formula should not be used.

Answer 3

Do you know the mass of the object? Without acceleration and mass, force can't be calculated.