JEE Physics Laws Of Motion MCQs Set B

Question. A boy is sitting on the horizontal platform of a joy wheel at a distance of 5 m from the center. The wheel begins to rotate and when the angular speed exceeds 1 rad/s, the boy just slips. The coefficient of friction between the boy and the wheel is (g = 10 m/s2)
(a) 0.5
(b) 0.32
(c) 0.71
(d) 0.2

Answer: A

Question. A train is running at 20 m/s on a railway line with radius of curvature 40,000 metres. The distance between the two rails is 1.5 metres. For safe running of train the elevation of outer rail over the inner rail is (g = 10 m/s2)
(a) 1.50 mm
(b) 1.25 mm
(c) 1.75 mm
(d) 2.0 mm

Answer: A

Question. A car is moving on a horizontal circular road of radius 0.1 km with constant speed. If coefficient of friction between tyres of car and road is 0.4, then speed of car may be (g = 10 m/s2)
(a) All of these
(b) 20 m/s
(c) 10 m/s
(d) 5 m/s

Answer: A

Question. A bomb of mass 9 kg explodes into two pieces of masses 3 kg and 6 kg. The velocity of mass 3 kg is 16 m/s. The kinetic energy of mass 6 kg in joule is
(a) 192
(b) 620
(c) 320
(d) 196

Answer: A

Question. A 6000 kg rocket is set for firing. If the exhaust speed is 1000 m/s, how much gas must be ejected each second to supply the thrust needed to overcome the weight of the rocket?
(a) 60 kg
(b) 50 kg
(c) 40 kg
(d) 30 kg

Answer: A

Question. Which of the following is self adjusting force?
(a) Static friction
(b) Limiting friction
(c) Dynamic friction
(d) Sliding friction

Answer: A

Question. An open carriage in a goods train is moving with a uniform velocity of 10 m/s. If the rain adds water with zero velocity at the rate of 5 kg/s, then the additional force required by the engine to maintain the same velocity of the train is
(a) 50 N
(b) Zero
(c) 20 N
(d) 0.5 N

Answer: A