# Machine Kinematics Questions and Answers – The Differential & Torques in Epicyclic Gear Trains

This set of Machine Kinematics Questions & Answers for Exams focuses on “The Differential & Torques in Epicyclic Gear Trains”.

1. To split the engine torque in two ways, which of the following device is used?
a) Clutch
b) Brake
c) Final drive
d) Differential

Explanation: The differential is a device that splits the engine torque two ways, allowing each output to spin at a different speed and hence considered as an immensely important device in the modern vehicles.

2. Two wheelers are also equipped with a differential.
a) True
b) False

Explanation: The differential is found on all modern cars and trucks, and also in many all-wheel-drive vehicles. Two wheelers do not have a differential.

3. Which of the following device allows the wheels of a car to rotate at two different speeds?
a) Clutch
b) Brake
c) Final drive
d) Differential

Explanation: The differential is a device that splits the engine torque two ways, allowing each output to spin at a different speed. The differential plays an integral role in how a car makes turns.

4. Which of the following is true regarding a differential?
a) The outer wheel rotates at a higher speed than the inner wheel
b) The outer wheel rotates at a lower speed than the inner wheel
c) Both the wheels rotate at the same speed
d) Front wheels rotate at a lower speed than rear wheel

Explanation: Since the outer wheels of a car has to travel a greater distance, the outer wheel must rotate at a higher speed in order to prevent slipping.

5. The ratio of speeds between gears is dependent upon the _________
a) Ratio of teeth between the two adjoining gears
b) Ratio of teeth between the two alternate gears
c) Ratio of acceleration
d) Ratio of velocity

Explanation: The ratio of speeds between gears is dependent upon the ratio of teeth between the two adjoining gears such that w1 x N1 = w2 x N2 where w1 is the teeth of gear one and N1 is the speed.

6. On a straight road motion, what is the purpose served by differential?
a) Equal torque to all the wheels
b) More torque to front wheels
c) More torque to rear wheels
d) More torque to opposite wheels

Explanation: When the car is traveling straight, both wheels travel at the same speed. This is done by providing equal torque to all the wheels.

7. Input torque acts on which of the following member?
a) Driven member
b) Driving member
c) Fixed member
d) Reciprocating member

Explanation: If the rotating parts of an epicyclic gear trains does not undergo any acceleration then it is kept in equilibrium by an externally applied torques. The input torque is one of them and acts on the driving member.

8. Resisting torque acts on which of the following member?
a) Driven member
b) Driving member
c) Fixed member
d) Reciprocating member

Explanation: If the rotating parts of an epicyclic gear trains does not undergo any acceleration then it is kept in equilibrium by an externally applied torques. The input torque is one of them and acts on the driven member.

9. Braking torque acts on which of the following member?
a) Driven member
b) Driving member
c) Fixed member
d) Reciprocating member

Explanation: If the rotating parts of an epicyclic gear trains does not undergo any acceleration then it is kept in equilibrium by an externally applied torques. The input torque is one of them and acts on the fixed member.

10. If the input power is increased to two times, what will be the effect of it on the fixed member power?
a) Has a 0 value
b) Increases by two times
c) Increases by 4 times
d) Decreases by two times

Explanation: Since the fixed member does not rotate, the power transmitted by it is 0. As a result of this it remains unaffected by change in input power.

11. If the ratio of angular velocities of the driven and driving torque is one, find the Braking torque
a) 0
b) 2
c) 4
d) 8

Explanation: We know the relation
T2 = -T1ω12
since the velocity ratio is 1
we have T2 + T1 = 0
now
T3 = T2 + T1
Therefore, T3 = 0.

12. The angular speed of the driven member is twice the driving member, if the input torque is 100 N-m,
Find the load torque magnitude in N-m.
a) 50
b) 100
c) 200
d) 25

Explanation: We know the relation
T2 = -T1ω12
since the velocity ratio is 12
we have T2 = 50 N-m.

13. Fixing torque’s value is independent of the load torque.
a) True
b) False

Explanation: Fixing torque or the braking torque or the Holding torque generally represented by T3 has a value
T3 = -(T2 + T1)
therefore its value is dependent on the load torque.

14. Load torque is directly proportional to the input angular velocity.
a) True
b) False

Explanation: We know that Load torque is given by
T2 = -T1ω12 where ω1 is the input angular velocity. Hence the given statement is correct.

Sanfoundry Global Education & Learning Series – Machine Kinematics.

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