Question

Suppose you pull a nail at a constant rate using a nail puller as shown inFigure 9.23. Is the nail puller in equilibrium? What if you pull the nail with some acceleration – is the nail puller in equilibrium then? In which case is the force applied to the nail puller larger and why?

Short answer

The force applied to the nail puller is more when the nail is pulled with acceleration.

Step-by-step solution

Force

A force is an external factor that can change the rest or motion of a body. It has a size and a general direction.

Explanation

When any object is in equilibrium, the force on the object is zero. For the figure 9.23, the forces acting on the nail is $F_{\circ }$. The reaction force by the nail is$F_n$ .

$F_I,\mathrm{N}$are the input force and the normal reaction by the wooden surface on the point of contact.

Now, for no acceleration,

$F_I+F_{\circ }=N$

The force$F_I$gives the counter clockwise torque and$F_n$gives clockwise torque. For no acceleration, the torques will be equal.

For, the acceleration of the nail in the upward direction, the force$F_{\circ }$is greater than the frictional force holding the nail. According to Newton’s law, the force by the nail on the nail puller$F_n$is also greater. So, the applied force$F_i$should increase for the acceleration of the nail.

Thus, when the nail is drawn with acceleration, the force delivered to the nail puller is greater.