Download Unit 5-Engineering Mechanics

Unit-05 Engineering Mechanics
Q1) A body continues in its state of rest or of uniform motion in a straight-line unless it is
compelled by an external force to change that state.
A) Newton’s Second Law B) Newton’s First Law C) Law of Conservation of Momentum
D) Newton’s Third Law.
Ans:- B
Q2) To every action, there is a equal and opposite reaction.
A) Newton’s Second Law
D) Newton’s Third Law.
Ans:- D
B) Newton’s First Law
C) Law of Conservation of Momentum
Q3) The rate of change of momentum of a body is proportional to the external force applied on
the body and takes place in the direction of force.
A) Newton’s Second Law
D) Newton’s Third Law.
Ans:- A
B) Newton’s First Law
C) Law of Conservation of Momentum
Q4) The quantity of matter contained in a body is
A) Weight of body B) Mass of Body C) Force in a body D b) Gravitational pull in a body
Ans:- B
Q5) The product of the mass of a body and its velocity is known as
A) Gravitational pull in a body B) Force in a body C) Momentum D) Weight of body.
Ans:- C
Q6)
The relation between One Newton (N) and dyne is
A) 10 10dyne
Ans :- C
B) 106 dyne
C) 105 dyne
D) 108 dyne
Q7) The mass of a person in a lift is 50 Kg. When the lift is going up with an acceleration 1 m/s2
then the vertical upward force acting on the person will be
A) 50N
B) zero
C) 550 N
D)55N
Ans:- C
Q8) The mass of a lift is 100 Kg. If it is falling down freely then the weight of 100 Kg body in it
will be
A) 200 Kg B) 10 Kg C) Zero D) 100 Kg
Ans:- C
Q9) A block of mass 2 Kg is lying on an inclined plane at an angle of 30° with the horizontal.
The coefficient of friction between the block and the plane is 0.7.The frictional force acting on
the inclined plane will be
A) 9.8 X 3N
B) 9.8X0.7X 3
N C) Zero D)9.8N
Ans: - B
Q10) A lift is moving upwards with an acceleration a. The force exerted by a person of mass M
on the floor of the lift will be
A) Mg –Ma
B)Ma
C) Mg
D)Mg + Ma
Ans: - D
11) Newton’s second law and third law of motion lead to the conservation of
A) Linear Momentum
B) Angular momentum
C) Potential Energy
D) Kinetic Energy
Ans:-A
12) A book is lying on the table. What is the angle between the action of the book on the table
and the reaction of the table on the book?
A) 0°
B) 30°
C) 45 °
D) 180°
Ans:- D
13) Unit of Torque is
A) Nm
Ans:-A
B) Kg
C) m/sec2
D) m/sec
14) A lift carries a weight of 100N and is moving with a uniform acceleration of 2.45m/sec2.the
tension in the cable when the lift is moving upward is:
A) 120N
B) 200N
C) 125N
D) 300N
Ans:- C
15) A lift carries a weight of 100N and is moving with a uniform acceleration of 2.45m/sec2.the
tension in the cable when the lift is moving downward is:
A) 120N
B) 200N
C) 125N
D) 75N
Ans:- D
15) The diagram shows a lift carrying weight and moving with a uniform acceleration. The
tension T when the lift is moving upwards
Cable supporting the lift
T
LIFT
W
A) W(1+a/g)
Ans:- A
B) W(1-a/g)
C) W(a/g)
D) Wg
16) The diagram shows a lift carrying weight and moving with a uniform acceleration. The
tension T when the lift is moving downwards
Cable supporting the lift
T
LIFT
W
A) W(1+a/g)
B) W(1-a/g)
C) W(a/g)
D) Wg
Ans:- B
17) A cage carrying 10 men each weighing 500N, starts moving downwards from rest in a mine
vertical shaft. The cage attains a speed of 12m/sec in 20 metres. Pressure exerted by 10 men on
the floor of the cage is
A) 316.326N
B) 3163.26N
C) 31.63N
D) 30N
Ans:- B
18) Two bodies of weight 50N and 30N are connected to the two ends of a light inextensible
string. The string is passing over a smooth pulley. The acceleration of the system is
A) 2.45m/sec2
B) 24.5m/sec2
C) 3m/sec2
D) 3.2 m/sec2
Ans:- A
19) Two bodies of different weights 60N & 32N are connected to the two ends by a light
inextensible string which passes over a smooth pulley. If the acceleration of the system is
3m/sec2 the tension developed in the string is
A) 41.73N
Ans: - A
B) 50N
C) 39.63N
D) 42.24N
20) A flywheel of an automobile acquires a speed of 2000 rpm in 45 seconds. Its angular
acceleration will be
A) 3rad/sec2
B) 4.654 rad/sec2 C) 8rad/sec2
D) 6rad/sec2
Ans:- B
21) The angle of rotation of a body is given by the equation
= t3 -4t2+10t+5.the angular
velocity of the body at t=0 is
A) 20 rad/sec B) 10 rad/sec C) 08rad/sec D) 02 rad/sec
Ans: - B
22) The rotation of a flywheel is governed by the equation
= 3t2- 2t +2. The angular
displacement at t=5 is
A) 120 radians
B) 112 radians C) 98 radians
D) 100 radians
Ans:-B
23) A luxury bus running with a speed of 90kmph comes to rest in a distance of 250m, when
brakes are applied. The diameter of the bus is 0.8m. The number of revolutions made by the
wheel
A) 99.47 B) 107 C) 105 D) 110
Ans: - A
24) If the tension in the cable supporting an elevator is equal to the weight of the elevator, the
elevator is
A) Going up with increasing speed
B) Going down with increasing speed
C) Going down with varying speed
D) Going up with uniform speed
Ans :- D
25) A flywheel rotates with uniform angular acceleration. Its angular velocity increases from
20 rad/sec to 40 rad/sec in 10 sec. How many rotations did make in this period?
A) 100
Ans:-B
B) 150
C) 200
D) 250
26) Displacement of a particle moving in a circular path is given by = 4t2+1. What is the
angular velocity of the particle after 5 sec
A) 8rad/sec
B) 40 rad/sec C) 25 rad/sec D) 30 rad/sec
Ans:- B
27) Moment of momentum is called as
A) Impulse B) Angular Momentum C) Couple
D) Kinetic Energy
Ans:- B
28) One radian is approximately equal to
A) 30
B) 45
C) 60
D) 90
Ans:- C
29) A wheel of 1m diameter is rotating at 60 rpm.What is the linear speed of a point on its
circumstance
A)
m/sec B) 2 m/sec C) (
Ans:- B
m/sec D) 3 m/sec