The rotational inertia of a disk about its axis is 0.70 Kg. m2. When a 2.0-kg weight is added to its rim, 0.40m from the axis, the rotational inertia becomes:
Correct answer: D. 1.02 kg - m2
- A. 0.38 kg - m2
- B. 0.54 kg - m2
- C. 0.86 kg - m2
- D. 1.02 kg - m2
Explanation
The correct answer is 1.02 kg - m2. The initial rotational inertia of the disk is 0.70 kg m2. When a 2.0 kg mass is added at a radius of 0.40 m, the additional moment of inertia is calculated using Im = m × r2. Substituting the values gives Im = 2.0 kg × (0.40 m)2 = 0.32 kg m2. Adding this to the original inertia results in a total of 1.02 kg m2. The other options underestimate the impact of the added mass, leading to incorrect calculations of the total rotational inertia.
This question appeared on the ETEA MDCAT 2016 paper, which you can sit online with every answer explained.
Report an error
The more specific you are, the faster it gets fixed. A source beats an opinion.
Prefer email? [email protected]
About Angular and Linear Quantities
Rotational motion relates angular displacement, angular velocity and angular acceleration to linear displacement, tangential velocity and tangential acceleration through the radius. Questions use radians, v equals r omega and tangential acceleration, while distinguishing tangential velocity from centripetal acceleration and angular quantities from their linear counterparts.
Practise Rotational and Circular Motion
521 free Rotational and Circular Motion MCQs from Physics, each with the correct answer and an explanation. Unlimited attempts, no account needed.
Discussion
Stuck on an option, or know a faster way to get there? Ask or explain it here.
No comments yet. Be the first to explain this one.
Exams that ask Physics questions like this
Physics is on 16 papers prepared for on TestUstad, and all of them draw the same bank, so this question is worth knowing for every one of them.
More Angular and Linear Quantities questions
A particle, held by a string whose other end is attached to a fixed point C, moves in a circle on a horizontal frictionless surface. If the string is cut, the angular momentum of the particle about the point: C.
The rotational analogue of mass in linear motion is:
A body Is moving in a circle of radius (r) with a variable speed, the acceleration of the body is:
A circular disc of mass M and radius R is rotating about it's with uniform speed v. Its kinetics energy is:
The moment of inertia of an object does not depend upon:
The speedometer of a car shows 36 km/hr. The angular speed of the wheels having 0.5m radius is: