NEET Physics Relative Velocity in Two Dimensions And Uniform Circular Motion MCQs Set A

a) The man cannot cross the river, in that way

b) He should start in a particular (calculated) direction making an obtuse angle with the direction of water current

c) He should start in such a way that, he moves normal to the bank, relative to the bank.

d) He should start normal to the river bank.

Answer: The man cannot cross the river, in that way

Question: A moves with 65 km/h while B is coming back of A with 80 km/h. The relative velocity of B with respect to A is

a) 15 km/h

b) 145 km/h

c) 60 km/h

d) 80 km/h

Answer: 15 km/h

Question: A boat crosses a river with a velocity of 8 km/h. If the resulting velocity of boat is 10 km/h then the velocity of river water is

a) 6 km/h

b) 8 km/h

c) 10 km/h

d) 4 km/h

Answer: 6 km/h

Question: A person aiming to reach the exactly opposite point on the bank of a stream is swimming with a speed of 0.5 m/s at an angle of 120° with the direction of flow of water. The speed of water in the stream is

a) 0.25 m/s

b) 0.433 m/s

c) 0.5 m/s

d) 1 m/s

Answer: 0.25 m/s

Question:

a)

b)

c)

d)

Answer:

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) 1

d)

Answer:  3

Question:

a)

b) drift of swimmer along river is zero

c) drift of swimmer along river will be 50 m

d) velocity of swimmer w.r.t ground is 2 m/s

Answer:

Question:  Centripetal acceleration is

a) not a constant vector

b) a magnitude changing vector

c) a constant scalar

d) a constant vector

Answer:  not a constant vector

Question:  Two stones are moving with same angular speeds in the radii of circular paths 1 m and 2 m. The ratio of their linear speed is ...X.... Here, X refers to

a) 1/2

b) 1/3

c) 3

d) 2

Answer: 1/2

Question: The direction of the angular velocity vector is along

a) the axis of rotation

b) the outward radius

c) the inward radius

d) the tangent to the circular path

Answer:  the axis of rotation

Question:  If a_r and a_t represent radial and tangential accelerations, the motion of particle will be uniformly circular, if

a)

b)

c)

d)

Answer:

Question:  In uniform circular motion

a) both acceleration and velocity change

b) both acceleration and speed are constant

c) acceleration and speed are constant but velocity changes

d) both velocity and acceleration are constant

Answer: both acceleration and velocity change

 More Questions.....................................

Question: A body is moving with a constant speed v in a circle of radius r. Its angular acceleration is

a) zero

b) vr²

c) v/r

d) vr

Answer:  zero

Question:

a) tangentially outward

b) radially inward

c) radially outward

d) None of these

Answer: tangentially outward

Question:  Choose the correct statement(s) from the following.
I. If speed of a body in a curved path is constant it has zero acceleration
II. When a body moves on a curved path with a constant speed, it has acceleration perpendicular to the direction of motion

a) II only

b) None of these

c) I only

d) I and II

Answer:  II only

Question:

a)

b)

c)

d)

Answer:

Question:

a)

b)

c)

d)

Answer:

Question: Assertion : The magnitude of velocity of two boats relative to river is same. Both boats start simultaneously from same point on one bank may reach opposite bank simultaneously moving along different paths.
Reason : For boats to cross the river in same time. The component of their velocity relative to river in direction normal to flow should be same.

a) Assertion is correct, reason is correct; reason is not a correct explanation for assertion

b) Assertion is correct, reason is incorrect

c) Assertion is incorrect, reason is correct

d) Assertion is correct, reason is correct; reason is a correct explanation for assertion

Answer:  Assertion is correct, reason is correct; reason is not a correct explanation for assertion

Question:  boat which has a speed of 5 km h^–1 in still water crosses a river of width 1 km along the shortest possible path in 15 minutes. The velocity of the river water is

a) 3 km h^–1

b) km h^–1

c) 4 km h^–1

d) None of these

Answer:  3 km h^–1

Question:  If rain falls vertically with a velocity V_r and wind blows With a velocity v_w from east to west, then a person standing on the roadside should hold the umbrella in the direction

a)

b)

c)

d)

Answer:

Question:

a)

b)

c)

d)

Answer:

Question:  An aircraft executes a horizontal loop of radius 1.00 km with a stedy speed of 900 km/h. The ratio of centripetal acceleration to acceleration due to gravity is [g = 9.8 m/s²]

a) 6.38

b) 9.98

c) 11.33

d) 12.13

Answer:  6.38

Question:

a)

b)

c)

d)

Answer:

Question:

a)

b)

c)

d)

Answer:

Question:  The length of second’s hand in a watch is 1 cm. The change in velocity of its tip in 15 seconds is:

a)

b)

c)

d) zero

Answer:

Question:

a)

b)

c)

d)

Answer:

Question:

a) 8 m s^–1

b) 0 m s^–1

c) 4 m s^–1

d) None of these

Answer:  8 m s^–1

Question:

a) 40 m/sec²

b)

c)

d)

Answer:  40 m/sec²

Question:  A stone tied to the end of a string of 1 m long is whirled in a horizontal circle with a constant speed. If the stone makes 22 revolution in 44 seconds, what is the magnitude and direction of acceleration of the stone?

a)

b)

c)

d)

None of these

Answer:

Question:  A cone filled with water is revolved in a vertical circle of radius 4 m and the water does not fall down. What must be the maximum period of revolution?

a) 4 s

b) 1 s

c) 6 s

d) 2 s

Answer: 4 s

Question:  A particle moves along a circle of radius R with constant angular velocity w. Its displacement magnitude in time t is :

a)

b)

c)

d)

Answer:

Question:  Two bodies are moving in concentric orbits of radii 2cm and 4 cm such that their time periods are the same. The ratio of their centripetal accelerations is :

a)

b)

c)

d) None of these

Answer:

Question:

a) 1 : 2

b) 2 : 1

c) 4 : 1

d) 1 : 1

Answer: 1 : 2

Question: A particle moves in a circle of radius 30 cm. Its linear speed is given by : V = 2t, where t in second and v in m/s. Find out its radial and tangential acceleration at t = 3 sec respectively.

a) 120 m/sec², 2 m/sec²

b) 220 m/sec², 50 m/sec²

c) 110 m/sec², 5 m/sec²

d) None of these

Answer: 120 m/sec², 2 m/sec²

Question: Centripetal acceleration is

a) None of these

b) a magnitude changing vector

c) a constant scalar

d) a constant vector

Answer:  None of these