Physics - Study Mode
[#361] Which conservation principle is applicable in the case of the motion of a rocket?
Correct Answer
(C) Conservation of momentum
Explanation
Solution: Rocket works on the principle of conservation of momentum. Rocket ejaculates gases in backward direction which creates momentum of the gases backwards and thus by conservation of momentum, the rocket gets a momentum in the forward direction making it to move forward.
[#362] Rocket works on the principle of
Correct Answer
(A) Newton's Third Law
Explanation
Solution: Rocket works on the principle of Newton's Third Law.
[#363] A passenger standing in a bus is thrown outward when the bus takes a sudden turn. This happens due to
Correct Answer
(B) Inertia of motion
Explanation
Solution: Newton's 1st law of inertia states that an object will change its direction when a force is applied to it. Hence, when a bus takes a sudden turn the passengers are thrown outward. This is due to the inertia of direction.
[#364] When a running car stops suddenly, the passengers tends to lean forward because of:
Correct Answer
(C) Inertia of motion
Explanation
Solution: When a running car stops suddenly, the passenger tends to lean forward because of inertia of motion. according to Newton's 1st law of motion, every bodies have nature to maintain inertia of rest or motion until there is no net force applied on that body.
[#365] A man stands in a lift which accelerates upwards. The resultant reaction force on the floor of the lift is
Correct Answer
(A) Greater than the weight of the man
Explanation
Solution: The weight of the man mg is acting on the floor. As the lift is moving up with an acceleration, say a, the man too in it is having this acceleration. The force producing this acceleration is ma. By Newton's third law, this force will have an equal reaction pressing the floor equal to ma. Therefore the total resultant reaction on the floor is mg+ma = m(g+a) which is mg, the weight of the man. So (a) is correct.