Which of the following is a class III lever? (a) Pair of scissors (b) Wheelbarrow (c) Crowbar (d) Human forearm

For a lever, a graph is plotted with load on Y-axis and effort on X-axis. Which of the following represents the slope of the graph? (a) Mechanical advantage (b) Velocity ratio (c) (d)

(a) When does the nucleus of an atom tend to become radioactive? (b) Name a single pulley in which displacement of load and effort is not the same. (c) State one advantage of this pulley.

A block and tackle system of pulleys has velocity ratio 4. (a) Draw a labelled diagram of the system indicating clearly, the direction of the load and the effort. (b) What is the value of the mechanical advantage of the given pulley system if it is an ideal pulley system?

Meera chose to use a block and tackle system of ‘9’ pulleys instead of a single movable pulley to lift a heavy load. (a) What is the advantage of using a block and tackle system over a single movable pulley? (b) Why should she connect more number of pulleys in the upper fixed block?

Given are two pulleys. (a) Copy and complete the labelled diagram connecting the two pulleys with a tackle to obtain Velocity Ratio = 2. (b) If Load = 48 kgf and efficiency is 80% then calculate: (i) Mechanical Advantage. (ii) Effort needed to lift the load.

Draw a block and tackle system of pulleys with velocity ratio equal to 3.

Three levers X, Y and Z of equal lengths are shown in the diagram. (a) Which class of lever do these belong to? (b) Among these (X, Y or Z), which one will give the maximum mechanical advantage? Justify your answer.

Case 1: Lata cuts a potato into two halves, using a cutter which belongs to a Class II lever. She needed effort E1. Case 2: Then she cuts one half of this potato again, but this time she needed effort E2. If E1 > E2 then: (a) In which case (1st or 2nd) was the potato closer to her hand applying the effort? (Assume normal reaction of the surface of the potato is same in both cases) (b) Give a reason for your answer in (a) above.

To lift a load of 30 kgf, Suhas uses a single fixed pulley while Radha uses a single movable pulley. The displacement of efforts in both cases is equal. In an ideal situation calculate the ratio of: (a) the efforts in the two cases. (b) the potential energy gained by the loads in the two cases. (c) the efficiencies in the two cases.

A cyclist stops pedalling while moving along a frictionless hilly road. Which quantity remains constant? (a) Kinetic energy (b) Potential energy (c) Total mechanical energy increases (d) Total mechanical energy remains constant

For a body to be in dynamic equilibrium: (a) its momentum must be zero (b) its acceleration must be zero (c) its kinetic energy must be zero (d) its velocity must be zero