JEE Physics Motion In A Plane MCQs Set A

Question. Which of the following is a vector?
(a) Acceleration
(b) Volume
(c) Time
(d) Current

Answer: A

Question. The change in a vector may occur due to
(a) Rotation of vector
(b) Rotation of frame of reference
(c) Translation of frame of reference
(d) None of this

Answer: A

Question. Which one of the following pair cannot be the rectangular components of force vector of 10 N?
(a) 9 N & 1 N
(b) 6 N & 8 N
(c) Both
(d) None of this

Answer: A

Question. Two vectors, each of magnitude A have a resultant of same magnitude A. The angle between the two vectors is
(a) 120°
(b) 150°
(c) 60°
(d) 30°

Answer: A

Question. Two forces of magnitude 8 N and 15 N respectively act at a point. If the resultant force is 17 N, the angle between the forces has to be
(a) 30°
(b) 90°
(c) 45°
(d) 60°

Answer: A

Question. Two forces of 10 N and 6 N act upon a body. The direction of the forces are unknown. The resultant force on the body may be
(a) 15 N
(b) 3 N
(c) 17 N
(d) 2 N

Answer: A

Question. If resultant of two vectors having magnitude 3 and 4 is 5. The magnitude of their cross product is
(a) 12
(b) 18
(c) 15
(d) 20

Answer: A

Question. A train is running at a constant speed of 90 km/h on a straight track. A person standing at the top of a boggey moves in the direction of motion of the train such that he covers 1 meters on the train each second. The speed of the person with respect to ground is
(a) 26 km/h
(b) 26 m/s
(c) 91 km/h
(d) 25 m/s

Answer: A

Question. A person, reaches a point directly opposite on the other bank of a flowing river, while swimming at a speed of 5 m/s at an angle of 120° with the flow. The speed of the flow must be
(a) 2.5 m/s
(b) 3 m/s
(c) 4 m/s
(d) 1.5 m/s

Answer: A

Question. A body of mass 1 kg is projected from ground at an angle 30º with horizontal on a level ground at a speed 50 m/s. The magnitude of change in momentum of the body during its flight is (g = 10 m/s2)
(a) 50 kg ms^–1
(b) 100 kg ms^–1
(c) 25 kg ms^–1
(d) 0

Answer: D

Question. A boat which has a speed of 5 km/hr in still water crosses a river of width 1 km along the shortest possible path in 15 minutes. The velocity of the river water (in km/hr) is
(a) 3
(b) 4
(c) 40
(d) 2

Answer: A

Question. The position coordinates of a projectile projected from ground on a certain planet (with no atmosphere) are given by y = (4t – 2t²)m and x = (3t) metre, where t is in second and point of projection is taken as origin. The angle of projection of projectile with vertical is
(a) 37°
(b) 30°
(c) 45°
(d) 60°

Answer: A

Question. A projectile is thrown into space so as to have a maximum possible horizontal range of 400 metres. Taking the point of projection as the origin, the co-ordinates of the point where the velocity of the projectile is minimum are
(a) (200, 100)
(b) (400, 100)
(c) (400, 200)
(d) (200, 200)

Answer: A

Question. Two paper screens A and B are separated by distance 100 m. A bullet penetrates A and B, at points P and Q respectively, where Q is 10 cm below P. If bullet is travelling horizontally at the time of hitting A, the velocity of bullet at A is nearly
(a) 700 m/s
(b) 600 m/s
(c) 200 m/s
(d) 100 m/s

Answer: A

Question. A particle P is moving in a circle of radius r with uniform speed v. C is the centre of the circle and AB is diameter. The angular velocity of P about A and C is in the ratio
(a) 2 : 1
(b) 4 : 1
(c) None of this
(d) 1 : 2

Answer: A

Question. A car is moving at a speed of 40 m/s on a circular track of radius 400 m. This speed is increasing at the rate of 3 m/s². The acceleration of car is
(a) 5 m/s²
(b) 3 m/s²
(c) 7 m/s²
(d) 4 m/s²

Answer: A

Question. The ratio of angular speeds of minute hand and hour hand of a watch is
(a) 12 : 1
(b) 6 : 1
(c) 60 : 1
(d) 1 : 60

Answer: A

Question. If speed of an object revolving in a circular path is doubled and angular speed is reduced to half of original value, then centripetal acceleration will become/remain
(a) Half
(b) Quadruple
(c) Double
(d) Same

Answer: A