A block of unknown mass is at rest on a smooth, hotizontal surface. A horizontal force of 47 N causes the block to accelerate at 4.2 m/s2. What is the weight of the block?

Question

A block of unknown mass is at rest on a smooth, hotizontal surface. A horizontal force of 47 N causes the block to accelerate at 4.2 m/s². What is the weight of the block?

I know there are two general equations: F=ma and W=mg. I have tried to combine these but get stuck. I know I can't use the W=mg equation and plug in the numbers, so what do I do?

Answer 1

You are correct with both of your equations, however this question just looks at how the mass responds to a known force (we call this inertial mass).

We just use F_net=ma

47 = m (4.2)

Therefore m=47/42 = 1.12 kg

Answer 2