Centre of gravity of the given square PQRO lies at:

1. (2, –2)
2. (3, –2)
3. (–2, 2)
4. (–2, 1)

An object is thrown vertically up. It reaches the highest point and then comes down. The work done by the force of gravity on the object is:

1. positive for both the way up and way down
2. negative for both the way up and way down
3. negative for the way up and positive for the way down
4. positive for the way up and negative for the way down

A crowbar of length 1.0 m has its fulcrum at a distance of 0.2 m from the load. The mechanical advantage of the crowbar is:

1. 5
2. 4
3. 3
4. 2

Which of the following figures will depict deviation of a ray of light through 90° when it emerges out of the prism.

1.

2.

3.

4.