The image above shows a block pulled across a table. the spring scale which measures in newtons, reads the force resisting the motion known as friction force. in the image above, what would be a reasonable measurement of friction force if normal force measured 100 newtons?

Frictional force = f = 30N

Explanation:

In the given statement coefficient of kinetic friction (µk) is not given. So, if we consider both block and table are made of wood then:

coefficient of kinetic friction = µk = 0.3  

Normal force = Fn = 100N

We know that:

Frictional force = f = µk × Fn

f = 0.3 × 100 = 30N

i believe the answer would be:

d. violin, clarinet, french horn, and tuba