Close a door by pushing on the doorknob. Close the door again using approximately the same force but applying it 5 centimeters away from the hinges. Try again by applying the force on the edge of the door in a direction pointing toward the hinges. Summarize and explain your observations. Comment on the difference between force and torque.

Check below for the explanation

Explanation:

a) Torque,

The larger the distance , r, the smaller the force needed to push the door, but the higher the torque.

The torque was larger when the force was applied 5 cm away than when it was applied at the knob because the distance becomes larger. The higher the distance, r, the larger the torque produced.

When the force was applied on the edge of the door in a direction pointing towards the hinge, the torque, τ became zero because the force was applied in the same direction to the the distance, r. i.e the angle, θ = 0.

b)Force is applied in a straight line, and the body accelerates in the direction of the force. The unit of force is Newton

Torque is the force applied at a distance from the center of rotation. It's unit is newton meters.

Torque is the time rate of change of angular momentum while force is the time rate of change of linear momentum

there are no contact forces mentioned on the list of choices that you've provided.