## Physics Test 2

Instructions

For the following questions answer them individually

Q 1

An object is placed 30 cm before a concave mirror of focal length of 20 cm to get a real
image. What will be the distance of the image from the mirror?

Q 2

A certain house hold has consumed 320 units of energy during a month. How much energy is this in joules?

Q 3

The radius of curvature of a concave mirror is 30 cm. Following Cartesian Sign Convention, its focal length is expressed as:

Q 4

Which of the following statements is/are INCORRECT?
A. The value of G on the moon is equal to that on the earth.
B. $$26.68 \times 10^{-11} N$$ is the force of gravitation between two point masses of 2 kg and 2 kg kept 1 m apart.
C. Newton’s law of gravitation is valid in the laboratory only.
D. Force is inversely proportional to the square of the distance between two bodies.

Q 5

Calculate the work done by the force of gravity when satellite moves in an orbit of
radius 40,000 km around the earth.