Mechanics (Part – 2) - Mock Test 365

Total Questions: 50

31. If action and reaction act on the same body, then______. [S.S.C. Online MTS (T-I) 16.09.2017 (Shift-III)]

(a) Result will be zero
(b) the body will not move
(c) the body will start moving
(d) only (a) and (b) are correct

Correct Answer: (a) Result will be zero

Solution:If action and reaction act on the same body, then according to Newton's third law of motion, if the values of action and reaction are equal, but the direction will be the opposite.

Hence their resultant force will be zero.

32. If two forces act on an object from opposite directions, then the magnitude of the net force acting on it is the_______of two forces. [S.S.C. Online MTS (T-I) 11.10.2021 (Shift-I)]

(a) difference
(b) sum
(c) ratio
(d) product

Correct Answer: (a) difference

Solution:Forces applied to an object in the same direction add to one another.

If two forces act in opposite directions on an object, the net force acting on it is the difference between the two forces.

33. Newton used the phrase "quantity of motion for _______ . [S.S.C. Online MTS (T-I) 13.10.2017 (Shift-II)]

(a) momentum
(b) force
(c) speed
(d) mass

Correct Answer: (a) momentum

Solution:Newton expressed the quantity of motion in terms of momentum.

Momentum is found only in a moving object, which is the product of the mass and velocity of the object.

$Momentum (p) = m \times v$

Where:

= momentum
= mass (in kg)
velocity (in m/s)

34. On what factors does the momentum of an object depend? [S.S.C. Online C.P.O.S.L. (T-I) 1.07.2017 (Shift-II)]

I. Mass of the object

II. Object speed

III. The volume of the object

(a) I only
(b) I and II only
(c) I and III only
(d) I, II, and III

Correct Answer: (b) I and II only

Solution:We know that, Momentum P=mv

Therefore, the momentum of an object depends on the mass of the object and the speed of the object.

Hence option (b) will be the correct answer.

35. A jet engine works on the principle of conservation of_______. [S.S.C. Online C.P.O.S.I. (T-I) 2.07.2017 (Shift-I)]

(a) Energy
(b) Mass
(c) linear momentum
(d) Angular momentum

Correct Answer: (c) linear momentum

Solution:A jet engine works on the principle of conservation of momentum, which is based on Newton’s Third Law of Motion.

Explanation:

The engine ejects high-speed gases backward (momentum is carried by the gases).
To conserve momentum, the jet moves forward with equal and opposite momentum.

36. When net torque is zero, _______ will be constant. [S.S.C. Online CHSL (T-I) 20.01.2017 (Shift-III)]

(a) force
(b) angular momentum
(c) linear momentum
(d) acceleration

Correct Answer: (b) angular momentum

Solution:When net torque is zero, angular momentum will be constant.

Torque is the rotational equivalent of force, and angular momentum is the rotational equivalent of linear momentum.

37. An athlete runs before taking a long jump, because________. [S.S.C. Online MTS (T-I) 20.09.2017 (Shift-III)]

(a) He covers a wide distance.
(b) It loses velocity
(c) He gains confidence by running
(d) He receives momentum

Correct Answer: (d) He receives momentum

Solution:A player participating in a long jump runs before jumping so that he can gain a greater amount of speed, that is, momentum.

This increased momentum enables him to make longer jumps.

38. A man is standing on a boat in still water. If he moves towards the shore, then the boat________. [S.S.C. Online MTS (T-I) 20.09.2017 (Shift-III)]

(a) will move away from the shore
(b) will reverse
(c) will move towards the shore
(d) will drown

Correct Answer: (a) will move away from the shore

Solution:If a person standing on a boat in still water moves towards the shore, he moves forward.

Therefore, as a reaction, a force is exerted on the boat away from the shore, due to which the boat will move away from the shore.

39. If an object moves in a purely rotatory motion, then each constituent particle of the body moves in a circle, the centre of which is located on a line is called________. [S.S.C. Online CHSL (T-I) 27.01.2017 (Shift-II)]

(a) the axis of rotation
(b) the line of rotation
(c) the spinning rod
(d) the fixed line

Correct Answer: (a) the axis of rotation

Solution:If an object moves in a purely rotatory motion, then each of its components moves in a circle, whose center lies on a line called the axis of rotation.

40. ______is the same at every point on a rotating body. [S.S.C. Online CHSL (T-I) 22.01.2017 (Shift-II)]

(a) Linear velocity
(b) Linear momentum
(c) Angular torque
(d) Angular velocity

Correct Answer: (d) Angular velocity

Solution:A rotating object has the same angular velocity at every point.

Angular velocity is the time rate at which an object rotates or revolves about an axis.It is measured in angle per unit of time.
Hence, the SI unit of angular velocity is radians per second.

« Previous 1 2 345 Next »

Mechanics (Part – 2)