## Physics A cyclist leans inwards when he is negotiating a curve so that

Necessary centripetal force may be available from the horizontal component of the normal reaction due to the track to maintain the curved motion.
He may increase his speed
No frictional force may be produced between the wheels and the axle
His weight may be reduced

## Physics A star appears twinkling in the sky because of

Refraction of light by atmosphere
Diffraction of light by atmosphere
Scattering of light by atmosphere
Reflection of light by atmosphere

Protons
Electrons
Photons
Photoelectrons

Wavelength
Amplitude
Frequency
Loudness

## Physics In which of the following cases, kinetic energy is being used in performing work ?

Paddling the bicycle to cover a distance
Rowing a boat in the lake
Wind mill grinding wheat grain
Driving a car to cover a distance

## Physics The velocity of heat radiation in vacuum is

Equal to that of light
Greater than that of light
Less than that of light
Equal to that of sound