(a) Define the moment of a force about a point.

[2 marks]

(b) The diagram shows a gripper which is used for hand strengthening exercises.

The diagram shows the gripper being squeezed.

In this situation, the gripper is in equilibrium.

The force produced by the fingers is equivalent to the single force X of magnitude 250 N acting in the direction shown in the diagram.

A force, Y, is exerted by the spring which obeys Hooke's law.

(i) Calculate the moment of force X about the pivot. State an appropriate unit.

[2 marks]

(ii) Calculate force Y.

[2 marks]

(iii) The extension of the spring is 15 mm. Calculate the spring constant k of the spring. Give your answer in N m–1.

[2 marks]

(iv) Calculate the work done on the spring to squeeze it to the position shown in the diagram.

[2 marks]

(Total 10 marks)