Engineering Physics Questions and Answers – Translational and Rotational Motion

This set of Engineering Physics Multiple Choice Questions & Answers (MCQs) focuses on “Translational and Rotational Motion”.

1. Two racing cars of masses m1 and m2 are moving in circles of radii r1 and r2 respectively. Their speeds are such that each makes a complete circle in the same time t. The ratio of the angular speeds of the first two to the second car will be ____________
a) 1:1
b) r1:r2
c) m1:m2
d) m1 m2:r1 r2
View Answer

Answer: a
Explanation: ω=v/r=2π/T
As both cars take some time for one revolution, so ω is same for both the cars.

2. A flywheel is attached to an engine to ___________
a) Increase its speed
b) Decrease its speed
c) Help in overcoming the dead point
d) Decrease its energy
View Answer

Answer: c
Explanation: Due to its large inertia of motion, a flywheel helps the engine to overcome the dead points.

3. Three identical metal balls, each of the radius r are placed touching each other on a horizontal surface such that an equilateral triangle is formed when centres of three balls are joined. The centre of the mass of the system is located at ___________
a) Line joining centres of any two balls
b) Centre of one of the balls
c) Horizontal surface
d) Point of intersection of the medians
View Answer

Answer: d
Explanation: The centre of mass of the system lies at the point of intersection of the medians that is at the centroid of the equilateral triangle.
advertisement
advertisement

4. A solid sphere of radius R is placed on smooth horizontal surface. A horizontal force F is applied at height h from the lowest point. For the maximum acceleration of the centre of mass, which is correct?
a) h=R
b) h=2R
c) h=0
d) no relation between h and R
View Answer

Answer: d
Explanation: The smooth horizontal surface does not provide any friction. The sphere does not roll. Hence the acceleration of centre of mass of the sphere is independent of the position of the applies force. There is no relation between h and R.

5. Statement 1: The earth is slowing down and as a result, the moon is coming nearer to it.
Statement 2: The angular momentum of the earth-moon system is not conserved.
a) Both statement 1 and 2 are true and statement2 is the correct explanation of the statement1
b) Both statement 1 and 2 are true but statement 2 is not the correct explanation of the statement1
c) Statement 1 is true but statement 2 is false
d) Statement 1 and 2 are false
View Answer

Answer: d
Explanation: Both the assertion and reason are false. The earth is not slowing down. The angular momentum of the earth-moon system is conserved.
Sanfoundry Certification Contest of the Month is Live. 100+ Subjects. Participate Now!

6. Statement 1: If ice caps of the pole melt, the day length will shorten.
Statement 2: Ice flows towards the equator and decreases the moment of inertia of the earth and hence increases the frequency of rotation of the earth.
a) Both statement 1 and 2 are true and statement2 is the correct explanation of statement 1
b) Both statement 1 and 2 are true but statement 2 is not the correct explanation of statement 1
c) Statement 1 is true but statement 2 is false
d) Statement 1 and 2 are false
View Answer

Answer: d
Explanation: Both the assertion and reason are false. As the polar ice melts, water so formed flows towards the equator. This increases the moment of inertia. To conserve angular momentum, frequency of rotation decreases and the day length becomes longer.

7. The direction of angular velocity vector is along ___________
a) The tangent to the circular path
b) The inward radius
c) The outward radius
d) The axis of rotation
View Answer

Answer: d
Explanation: If we wrap the right hand around the axis of rotation with the fingers pointing in the direction of rotation, then the thumb points in the direction of angular velocity.
advertisement

8. The motion of planets in the solar system is an example of the conservation of ___________
a) Mass
b) Linear momentum
c) Angular momentum
d) Energy
View Answer

Answer: a
Explanation: The motion of planets around the sun is an example of the conservation of angular momentum.

9. A body of mass M while falling vertically downwards under gravity breaks into two parts, a body B of mass 1/3 M and body C of mass 2/3 M. The centre of mass of bodies B and C taken together shifts compared to that of body A towards ___________
a) Body C
b) Body B
c) Depends on the height of braking
d) Does not shift
View Answer

Answer: d
Explanation: The centre of mass bodies B and C does not shift compared to body A. It continues to move vertically downwards under the effect of gravity. This is because there is no new external force acting on the system.
advertisement

10. The instantaneous acceleration of the point of contact during rolling is zero.
a) True
b) False
View Answer

Answer: b
Explanation: As the body is rotating, its instantaneous acceleration cannot be zero.

Sanfoundry Global Education & Learning Series – Engineering Physics.

To practice all areas of Engineering Physics, here is complete set of 1000+ Multiple Choice Questions and Answers.

If you find a mistake in question / option / answer, kindly take a screenshot and email to [email protected]

advertisement
advertisement
Subscribe to our Newsletters (Subject-wise). Participate in the Sanfoundry Certification contest to get free Certificate of Merit. Join our social networks below and stay updated with latest contests, videos, internships and jobs!

Youtube | Telegram | LinkedIn | Instagram | Facebook | Twitter | Pinterest
Manish Bhojasia - Founder & CTO at Sanfoundry
Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He lives in Bangalore, and focuses on development of Linux Kernel, SAN Technologies, Advanced C, Data Structures & Alogrithms. Stay connected with him at LinkedIn.

Subscribe to his free Masterclasses at Youtube & discussions at Telegram SanfoundryClasses.