MCQ practice · SSC Physics Board questions · Chapter 3: Force
A backward (recoil) velocity is obtained in:
- i. a boat
- ii. a gun
- iii. a rocket
Think it through first, then pick an option.
- a i and ii
- b ii and iii
- c i and iii
- d i, ii and iii
Answer and explanation
Correct answer: d i, ii and iii
All three are true: in a boat, a gun and a rocket the total momentum starts at zero, so when one part goes one way the other gets a recoil the opposite way.
Why the other options are wrong
- a i and ii: iii is also true: when the rocket throws gas down, it rises with the same kind of recoil, so this option is incomplete.
- b ii and iii: i is also true: when the boatman jumps to the bank the boat slides back, so this option is incomplete.
- c i and iii: ii is also true: the gun is pushed back when the bullet is fired, so this option is incomplete.
More board questions on this topic
- When a bullet is fired from a gun:
- What is the combined velocity of the two bodies?
- In which direction will the combined bodies move?
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