Free NEET Physics multiple-choice questions on Relative Motion 1D & 2D. Attempt each question and reveal the answer with a full explanation.
A man is walking on a level road at 3 km/h . Raindrops fall vertically with a speed of 4 km/h . The velocity of raindrops relative to the man is: 5 km/h 7 km/h 1 km/h 7 km/h A swimmer can swim in still water at 4 km/h . The river flows at 3 km/h . To cross the river in the shortest time, the swimmer should swim at an angle with the upstream direction of: 90 120 30 0 If a vector 2 i+3 j+8 k is perpendicular to the vector 4 j-4 i+ k , then the value of -1 - 1 2 1 2 1 If the angle between the vector A and B is , the value of the product ( B A). A is equal to - Zero BA 2 BA 2 BA 2 The vectors A and B are such that | A + B| = | A - B| . The angle between the two vectors is:- 90 60 75 45 A and B are two vectors and is the angle between them, if | A B | = 3 ( A . B ) , the value of is 45° 30° 90° 60° A body, under the action of a force F =6 i -8 j +10 k , acquires an acceleration of 1 m/s 2 . The mass of this body must be : 10 2 kg 2 10 kg 10 kg 20 kg A particle is moving such that its position coordinate (x, y) are (2m, 3m) at time t = 0 (6m, 7m) at time t = 2 s and (13m, 14m) at time t = 5 s . Average velocity vector ( V av ) from t = 0 to t = 5 s is :- 1 5 (13 i +14 j ) 7 3 ( i + j ) 2( i + j ) 11 5 ( i + j ) If the magnitude of sum of two vectors is equal to the magnitude of difference of the two vectors, the angle between these vectors is :- 0° 90° 45° 180° The angle between A - B and A B is ( A B ) : 60 90 120 45 A motorboat covers a given distance in 6 hours moving downstream on a river. It covers the same distance in 10 hours moving upstream. The time it takes to cover the same distance in still water is: 7.5 hours 8 hours 6.5 hours 9 hours A river is flowing from West to East with a speed of 5 m/min . A man can swim in still water at a speed of 10 m/min . If he wants to cross the river in the shortest time, in which direction should he swim? Due North 30 East of North 30 West of North 60 East of North Preeti reached the metro station and found that the escalator was not working. She walked up the stationary escalator in time t 1 . On other days, if she remains stationary on the moving escalator, then the escalator takes her up in time t 2 . The time taken by her to walk up on the moving escalator will be: t 1 t 2 / (t 1 + t 2) t 1 t 2 / (t 2 - t 1) (t 1 + t 2) / 2 t 1 + t 2 The speed of a swimmer in still water is 20 m/s . The speed of river water is 10 m/s and is flowing due east. If he is standing on the south bank and wishes to cross the river along the shortest path, the angle at which he should make his strokes w.r.t. north is: 30 west 30 east 60 west 0 Rain is falling vertically with a speed of 35 m/s . A woman rides a bicycle with a speed of 12 m/s in east to west direction. What is the direction in which she should hold her umbrella? = -1 (12/35) with the vertical = -1 (35/12) with the vertical = -1 (12/35) with the horizontal = -1 (35/12) with the horizontal A bus is moving with a speed of 10 m/s on a straight road. A scooterist wishes to overtake the bus in 100 s . If the bus is at a distance of 1 km from the scooterist, with what speed should the scooterist chase the bus? 20 m/s 40 m/s 25 m/s 10 m/s The speed of a boat is 5 km/h in still water. If it crosses a river of width 1 km along the shortest possible path in 15 minutes, then the velocity of the river's water is: 3 km/h 4 km/h 2 km/h √ 41 km/h A bullet is fired from a rifle. If the rifle recoils freely, the kinetic energy of the rifle is: Less than that of the bullet More than that of the bullet Same as that of the bullet Zero The speed of a boat in still water is 15 km/h . It goes 30 km upstream and returns downstream to the starting point in a total time of 4.5 hours . The speed of the river flow is: 5 km/h 10 km/h 3 km/h 2 km/h The speed of a boat is 5 km/h in still water. If it crosses a river of width 1 km along the shortest path in 15 min , the velocity of the river's water is: 3 km/h 4 km/h 2 km/h 5 km/h A man runs at a speed of 10 m/s due West and rain falls vertically at 10 m/s . The angle at which the man should hold his umbrella with the vertical to protect himself from rain is: 45 towards West 30 towards West 45 towards East 60 towards West The speed of a boat is 5 km/h in still water. It crosses a river of width 1 km along the shortest possible path in 15 minutes. The velocity of the river water is: 3 km/h 4 km/h 2 km/h 5 km/h A train 100 m long is moving with a velocity of 10 m/s . A bird is flying in the opposite direction with a velocity of 5 m/s . The time taken by the bird to cross the train is: 6.67 s 10 s 20 s 15 s A man can swim in still water at 4 km/h . He wants to cross a river 1 km wide that flows at 2 km/h to reach the point directly opposite to his starting point. At what angle to the river flow should he swim? 120 30 60 150 A boat moves with a speed of 5 km/h relative to water in a river flowing with a speed of 3 km/h due East. To cross to a point on the opposite bank directly North, in what direction should the boat be steered? 37 West of North 37 East of North 53 West of North 53 East of North A car moves at 80 km/h North and another car moves at 80 km/h East. The velocity of the first car relative to the second car is: 80 2 km/h North-West 80 2 km/h North-East 0 km/h 160 km/h South-West A motorboat covers the distance between two spots on the river in 8 hours and 12 hours downstream and upstream respectively. What is the time required by the boat to cover this distance in still water? 9.6 hours 10 hours 11.2 hours 8.4 hours The speed of a boat in still water is 5 km/h . If it crosses a river of width 1 km in 15 minutes along the shortest possible path, then the velocity of the river's water is: 3 km/h 4 km/h 2 km/h 41 km/h A stone is dropped from a height h . Simultaneously, another stone is thrown up from the ground with velocity v . The two stones cross each other after a time: h/v v/g 2h/g h/2v A river is 1 km wide. The water flows at 3 km/h . A swimmer whose speed in still water is 4 km/h wishes to cross the river in the shortest possible time. How far downstream is he carried? 750 m 1000 m 250 m 667 m Rain is falling vertically with a speed of 30 m/s. A man rides a bicycle at 10 m/s in the north to south direction. The relative velocity of rain with respect to the man is: 10 10 m/s 20 m/s 40 m/s 10 2 m/s The speed of a boat in still water is 5 km/h. It crosses a river of width 1 km along the shortest possible path in 15 minutes. The velocity of the river water is: 3 km/h 4 km/h 2 km/h 5 km/h A football player is moving southward and suddenly turns eastward with the same speed to avoid an opponent. The force that acts on the player while turning is Along eastward Along northward Along north-east Along south-west A motorboat is moving across a river of width w . The river flows with velocity u . The boat's velocity relative to the water is v . The minimum time to cross the river is: w/v w/ v 2-u 2 w/u w/(v+u) A ship A is moving Westwards with a speed of 10 km/h and a ship B which is at 100 km South of A, is moving Northwards with a speed of 10 km/h . The time after which the distance between them becomes shortest, is: 5 h 5√2 h 10√2 h 0 h Two particles A and B are connected by a rigid rod of length L . The rod slides along perpendicular rails as shown. If the velocity of A to the left is v , then the velocity of B downwards is: v v v v A motorboat is racing towards north at 25 km/h and the water current in that region is 10 km/h in the direction of 60 east of south. The magnitude of the resultant velocity of the boat is: 22 km/h 35 km/h 15 km/h 25 km/h A man can swim at a speed of 3 km/h in still water. He wants to cross a 500 m wide river flowing at 2 km/h . He keeps himself always at an angle of 120 with the river flow while swimming. The time taken by him to cross the river is: 1 3 3 h 1 6 h 1 3 h 1 3 h An airplane flies from a point A to B (distance L ) and back in still air with speed v . If a wind blows with speed u perpendicular to the line AB , the total time taken for the round trip is: 2L v 2 - u 2 2L v 2L v+u 2L v 2 + u 2 Two cars are moving in the same direction with the same speed v . They are separated by a distance d . A third car moving in the opposite direction meets these two cars at an interval of t . The speed of the third car is: d/t - v d/t + v v - d/t d/t Two particles A and B , move with constant velocities v 1 and v 2 . At the initial moment their position vectors are r 1 and r 2 respectively. The condition for them to collide is: r 1 - r 2 | r 1 - r 2| = v 2 - v 1 | v 2 - v 1| r 1 - r 2 = v 2 - v 1 r 1 v 1 = r 2 v 2 r 1 v 1 = r 2 v 2 A person standing on an open car moving with a constant velocity of 10 m/s on a horizontal road throws a ball vertically upward (relative to himself) with a speed of 20 m/s . The distance covered by the ball in the air with respect to the ground is ( g = 10 m/s 2 ): 80 m 40 m 100 m 60 m A boat is sent across a river with a velocity of 8 km/h . If the resultant velocity of boat is 10 km/h , then the velocity of the river is: 6 km/h 4 km/h 2 km/h 8 km/h A man can swim in still water with a speed of 4 km/h . He wants to cross a river 1 km wide that flows at 3 km/h . If he swims perpendicular to the river current, how far down the river will he reach the other bank? 750 m 500 m 1 km 250 m A particle is moving such that its position coordinates (x, y) are (2 m , 3 m ) at time t = 0 , (6 m , 7 m ) at time t = 2 s and (13 m , 14 m ) at time t = 5 s . Average velocity vector v avg from t=0 to t=5 s is: 1 5 (11 i + 11 j ) 1 5 (13 i + 14 j ) 7 3 i + 7 3 j 11 i + 11 j A body is moving with velocity 30 m/s towards east. After 10 seconds its velocity becomes 40 m/s towards north. The average acceleration of the body is: 5 m/s 2 1 m/s 2 7 m/s 2 √7 m/s 2 Two bodies A and B are moving with velocities v A and v B making an angle with each other. The magnitude of the relative velocity of A w.r.t B is: √(v A 2 + v B 2 - 2v Av B cos ) √(v A 2 + v B 2 + 2v Av B cos ) v A - v B v A + v B