Physics - Study Mode
[#1086] Mirage is due to:
Correct Answer
(A) Unequal heating of different parts of the atmosphere
Explanation
Solution: Mirages happen when the ground is very hot and the air is cool. The hot ground warms a layer of air just above the ground. When the light moves through the cold air and into the layer of hot air it is refracted (bent). A layer of very warm air near the ground refracts the light from the sky nearly into a U-shaped bend.
[#1087] Light from the Sun reaches us in nearly
Correct Answer
(C) 8 minutes
(G) 8 min
Explanation
Solution: The light from the sun takes about 8 minutes to reach the Earth after it has been emitted from the sun's surface.
[#1088] What is the direction of torque?
Correct Answer
(A) Perpendicular to the direction of applied force
Explanation
Solution: The direction of torque is perpendicular to the direction of applied force.
[#1089] The motion of a body around a circular path is an example of
Correct Answer
(A) Uniform velocity, variable acceleration
Explanation
Solution: Uniform circular motion occurs when a body moves in a circular path with constant velocity. The acceleration of a body experiencing uniform circular motion is always directed toward the center of the circle (centripetal acceleration or a c = V 2 / r where v is the body’s velocity, and r is the radius of the circle). This acceleration is constant in magnitude but changes in direction, so, it is variable at every point of the circular path.
[#1090] What should a person on a freely rotating turn table do to decrease his (angular) speed ?
Correct Answer
(C) Spread his hands outwards
Explanation
Solution: When a person on a turn table will raise his hands, there will be increase in the momentum of inertia. Hence, the angular velocity of the turntable will decrease.