If in a simple pendulum experiment the length of the inextensible string is increased by a factor of four, its period is increased by a factor of?

• A. 4
• B. π/2
• C. 1/4
• D. 2

A piece of stone attached to one end of a string is whirled round in a horizontal circle and the string suddenly cuts. The stone will fly off in a direction

• A. perpendicular to the circular path
• B. parallel to the circular path
• C. tangential to the circular path
• D. towards the center of the circle

A car of mass 800kg attains a speed of 25m/s in 20 secs. The power developed in the engine is

• A. 1 . 25 x 10⁴ W
• B. 2 . 50 x 10⁴ W
• C. 1 . 25 x 10⁶ W
• D. 2 . 50 x 10⁶ W

If a ball released from a height of 20m, How long would it take the ball to reach the ground? (assures g = 10m/s)

• A. 2sec
• B. 3sec
• C. 35sec
• D. 2.4sec

A motorcyclist, passing a road junction, moves due west for 8 s at a uniform speed of 5ms^-1. He then moves due north for another 6 s with the same speed. At the end of the 6s his displacement from the road junction is 50m in the direction of

• A. N53^oE
• B. N37^oE
• C. N53^oW
• D. N37^oW

(a) Write down the names of two particles used in explaining the wave nature of matter.

(b) State the wave characteristics which are exhibited by the particles named in (a) above.

A cup containing 100g of pure water at 20°C is placed in a refrigerator. If the refrigerator extracts heat at a rate of 840J per minute, calculate the time taken for the water to freeze. Neglect the heat capacity of the material of the cup. (Specific heat capacity of water =4.2J\(g^{-1}K^{-2}\))((Specific latent heat fusion of water =336J\(g^{-1}\)

• A. 15minutes
• B. 20 minutes
• C. 42 minutes
• D. 50 minutes

Electrical appliances in homes are normally earthed so that

• A. a person touching the appliances is safe from electric shock
• B. both the a.c. and d.c. sources can be used
• C. the appliances are maintained at a higher pd than the earth
• D. the appliances are maintained at a lower pd than the earth

The S.I unit of moment of a force is

• A. kgm
• B. Nm
• C. Jm
• D. µm

A screw-jack has the distance between its successive threads as P and the length of its tommy bar as r. Its velocity ratio is given by the expression

• A. \(\frac{2 \pi r^2}{P}\)
• B. \(\frac{2 \pi r}{P}\)
• C. \(\frac{2 \pi}{rp}\)
• D. \(\frac{P}{2 \pi r}\)