Page 70 - CITS - WCS - Mechanical

WORKSHOP SCIENCE - CITS

Assignment:
1. Which of the following is NOT true for an object moving along a straight path in an accelerated motion?

a. Its velocity always changes
b. Its speed keeps changing
c. (d) It always goes away from the Earth
d. It always goes away from the Earth
Answer: c. A force is always acting on it
Explanation: For the accelerated motion of an object along a straight line, a non-zero force must be acting on
the object, which is increasing its velocity and speed. However, the direction of force is not given so it can’t be
determined whether it is moving away from earth or not.
2. The inertia of an object causes the object to
a. decrease its speed
b. Increase its speed
c. resist any change in the state of its motion

d. decelerate due to friction
Answer: (c) resist any change in the state of its motion
Explanation: The inertia of an object causes the object to resist any change in the state of its motion.
3. Which of the following is true for the third law of motion?
a. Action-Reaction pair always acts on the same body.
b. They act on different bodies in opposite directions
c. Action-Reaction pairs have the same magnitudes and directions
d. Act on either body at normal to each other
Answer: (b) They act on different bodies in opposite directions.
Explanation: Action-Reaction always acts on different bodies in opposite direction and are equal in magnitude.
4. Which of the following is the SI units of force?

a. Kgm/s2
b. Kgm/-s
c. Newton-metre
d. Newton
Answer: (d) Newton
Explanation: Newton is the SI unit of force.
5. If the mass of the body is doubled and its velocity becomes half, then the linear momentum of the body will
a. become double
b. remain the same

c. become half
d. become four times
Answer: (b) remain the same
Explanation: If the body’s mass is doubled and its velocity becomes half, then the body’s linear momentum will
remain the same.
6. The linear momentum of an object is 250 g cm/s. If the velocity of the object is 5 m/s, then the mass of the
object is
a. 0.5 g
b. 5 kg

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CITS : WCS - Mechanical - Exercise 4 CITS : WCS - Mechanical - Exercise 4