Physics Past Questions and Answers

The diagram above represents balls in an undulating surface. Which of the following option represents positions of stable equilibrium?

A III, IV and VIII
B II, V and VIII
C III, VI and IX
D I, IV and VII

Question 72:

A bob of weight 0.1 N hangs from a massless string of length 50 cm. A variable horizontal force which increase from zero is applied to pull the bob until the string makes an angle of 60o with the vertical. The work done is

A 0.500 J
B 0.250 J
C 0.050 J
D 0.025 J

Question 73:

Two metals P and Q of length l₁ and l₂ are heated through the same temperature difference. If the ratio of the linear expansivities of P to Q is 2:3 and the ratio of lengths is 3:4. What is the ratio of increase in length of P to Q?

A 7:5
B 5:7
C 1:2
D 2:1

Question 74:

THe velocity of sound in air at 16^oC is 340ms^-1. What will it be when the pressure is doubled and its temperature raised to 127^oC?

A 400 ms^-1
B 4,000 ms^-1
C 8,000 ms^-1
D 160,000 ms^-1

Question 75:

Three capacitors of capacitance 2Î¼F, 4Î¼Fand 8Î¼F are connected in parallel and a P.D of 6V is maintained across each capacitor, the total energy stored is

A 2.52 x 10^-6J
B 6.90 x 10^-6J
C 2.52 x 10^-4J
D 6.90 x 10^-4J