1. The angular velocity (in rad/s) of a body rotating at N r.p.m. is
a) π N/60
b) 2 π N/60
c) π N/120
d) π N/180
Answer: b
Explanation: Angular velocity is defined as the rate of change of
angular displacement with respect to time. It is usually expressed by a
Greek letter ω (omega). Mathematically, angular velocity, ω =dθ/dt
If a body is rotating at the rate of N r.p.m. (revolutions per minute), then its angular velocity, ω = 2πΝ / 60 rad/s
2. The linear velocity of a body rotating at ω rad/s along a circular path
of radius r is given by
a) ω.r
b) ω/r
c) ωs2.r
d) ωs2/r
Answer: a
Explanation: If the displacement is along a circular path, then the
direction of linear velocity at any instant is along the tangent at that point. therefore, the linear velocity will be
ω.r
3. When a particle moves along a straight path, then the particle has
a) tangential acceleration only
b) centripetal acceleration only
c) both tangential and centripetal acceleration
d) none of the mentioned
Answer: a
Explanation: The acceleration of a particle at any instant moving along a
circular path in a direction tangential to that instant, is known as
tangential component of acceleration or tangential acceleration.
4._______________ is the simplest type of motion and is along a straight
line path. a) plane motion
b) rectilinear motion
c) curvilinear Motion
d) none of the mentioned
Answer: b
Explanation: Rectilinear Motion is the simplest type of motion and is
along a straight line path. Such a motion is also known as translatory
motion.
5.A train covers 60 miles between 2 p.m. and 4 p.m. How fast was it
going at 3 p.m.?
a) 60 mph
b) 30 mph
c) 40 mph
d) 50 mph
Answer: b
Explanation: The speed is traveled distance (60 miles) divided by traveled
time (4pm – 2pm = 2hours):
60 miles/ 2 hours = 30 mph
6.The relative velocity of B with respect to A in a rigid link AB is
a) parallel to AB
b) perpendicular to AB
c) along AB
d) at 450
Answer: b
Explanation: The relative velocity of any two points on a rigid link is
always normal to the line joining the two points. 7. The magnitude of linear velocity of a point B on a link AB relative to
point A is
a) ω x AB
b) ω(AB)2
c) ω2AB
d) (ω x AB)2
Answer: a
8.ABCD is a four bar mechanism in which AB = 310mm and CD =
450mm. AB and CD are both perpendicular to the fixed link AD. If the
velocity of B at this condition is v. Then the velocity of C is
a) v
v) 2/3 v
c) 3/2 v
d) 9/4 v
Answer: c
Explanation: Velocity at C = CD/AB x velocity at B
= 450/310 x v = 3/2 v
9. A thin circular disc is rolling with a uniform linear speed, along a
straight path on a plane surface. Which of the following statement is
correct in this regard?
a) All points of the disc have the same velocity.
b) The centre of the disc has zero acceleration.
c) The centre of the disc has centrifugal acceleration.
d) The point on the disc making contact with the plane surface has zero
acceleration.
Ans=b
10. When a point moves along a straight line, its acceleration will have
a) radial component only
b) tangential component only
c) coriolis component only
d) radial and tangential components both
Answer: b
Explanation: The tangential component, is parallel to the velocity of the
particle at the given instant. The centripetal or radial component, is perpendicular to the velocity of
the particle at the given instant.
11. Which of the following disciplines provides study of inertia forces
arising from the combined effect of the mass and motion of the parts?
a) theory of machines
b) applied mechanics
C) kinematics
d) kinetics
Answer: d
Explanation: The study of inertia forces arising from the combined
effect of the mass and motion of the parts is called kinetics. The study of relative motion between the parts of a machine is called
kinematics. The study of the relative motion between the parts of a machine and the
forces acting on the parts is called theory of machines.
12.A wheel accelerates uniformly from rest to 2000 r.p.m. in 20 seconds. What is its angular acceleration?
a) 10.475 rad/s2
b) 12 rad/s2
c) 14 rad/s2
d) 15 rad/s2
Answer: a
Explanation: Solution. Given : N0 = 0 or ω = 0 ; N = 2000 r.p.m. or ω =
2π × 2000/60 = 209.5 rad/s ; t = 20s
Angular acceleration
Let α = Angular acceleration in rad/s2
We know that
ω = ω0 + α.t
or 209.5 = 0 + α × 20
or α = 209.5 / 20 = 10.475 rad/s2
13.When a particle moves with a uniform velocity, then dv/dt will be
a) infinitely small
b) zero
c) infinitely great
d) none of the mentioned
Answer: b
Explanation: When a particle moves with a uniform velocity, then dv/dt
will be zero. In other words, there will be no tangential acceleration; but
the particle will have only normal or radial or centripetal acceleration.
14.The force which acts along the radius of a circle and directed
____________ the centre of the circle is known as centripetal force. a) away from
b) towards
c) at the
d) none of the mentioned
Answer: b
Explanation: Centripetal force acts radially inwards and is essential for
circular motion. 15.The unit of mass moment of inertia in S.I. units is
a) m4
b) kgf-m-s2
c) kg-m2
d) N-m
Ans=c
16.The energy possessed by a body, for doing work by virtue of its
position, is called
a) potential energy
b) kinetic energy
c) electrical energy
d) chemical energy
Answer: a
17. Which of the following cases momentum is conserved?
a) Perfectly elastic collision
b) Inelastic collision with 0<e<1
c) Perfectly inelastic collision
d) Momentum is always conserved
Answer: d
Explanation: When the net external force acting on the body is 0, the
linear momentum is always conserved no matter the type of collision.
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