Question

1.A student attaches a string to a puck on a frictionless air table, and pulls with a constant force on the puck. a. Draw the force diagram for the puck during the pull. B. Describe the net force on the puck during the pull. C. Describe the motion of the puck during the pull.

Answer 1

a)

for the puck :

F = force applied in the direction of pull

N = normal force on the puck in upward direction by the surface of table

W = weight of the puck in down direction due to force of gravity

b)

along the vertical direction , normal force balance the weight of the puck , hence the net force is same as the force of pull F .

so  F = ma                                    where m = mass of puck  , a = acceleration

Fnet = F

c)

since the net force acts in the direction of force of pull F , hence the puck accelerates in the same direction .