Physics
Which of the following statements is incorrect?
- For a machine, velocity ratio does not change.
- Due to friction, mechanical advantage of a machine increases.
- For an ideal machine, work output is equal to the work input.
- For an ideal machine, mechanical advantage is numerically equal to the velocity ratio
Machines
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Answer
Due to friction, mechanical advantage of a machine increases.
Reason — Friction reduces the mechanical advantage of a machine because frictional forces oppose motion, which means they can decrease the efficiency of a machine by dissipating energy as heat. This results in a decrease in the mechanical advantage of the machine.
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Related Questions
Which of the following is not an example of a machine used as a force multiplier?
- A jack used to lift a car.
- A single fixed pulley used to lift a bucket of water from a well.
- A bar used to lift a heavy stone.
- A wheel barrow used to carry a load.
For an ideal machine:
- Output energy = Input energy
- Output energy > Input energy
- Output energy < Input energy
- Work output > Work input
Unit of velocity ratio is:
- Nm
- Joule
- Newton
- No unit
The correct relationship between the mechanical advantage (M.A.), velocity ratio (V.R.) and efficiency (η) is:
- M.A. = η x V.R.
- V.R. = η x M.A.
- η = M.A. x V.R.
- None of these