1. Fyodor Pirotsky
2. Arthur Pitney
3. Fritz Pfleumer
4. Stephen Perry
Option “2” is correct. Postage Meter was invented by Arthur Pitney.
492. Who invented Helicopter?
1. Copernicus
2. Sikorsky
3. Cockrell
4. Drinker
Option “2” is correct. Igor Sikorsky, a Russian is recognized as father of modern helicopters.
493. If ice floating on water in a vessel melts, the water level in the vessel _______.
1. Increases
2. Does not change
3. First increases before decreasing
4. Decreases
Option “2” is correct. The water level remains the same when the ice cube melts. A floating object displaces an amount of water equal to its own weight. Since water expands when it freezes, one ounce of frozen water has a larger volume than one ounce of liquid water.
494. If in a motion, the axis of the rotation does not pass through the object, then the motion is called ________.
Option “4” is correct. The Orbital Motion Interactive is simulates the elliptical motion of a satellite around a central body. In this type of motion axis of the rotation does not pass through the object.
495. What are the two kinds of Rotatory motion?
1. Spin and Vibrational motion
2. Spin and Orbital motion
3. Spin and Translatory motion
4. Spin and Projectile motion
Option “2” is correct. Spin and Orbital motion are the two kinds of Rotatory motion.
496. Rate of change of momentum is –
1. Area
2. Pressure
3. Force
4. Velocity
Option “3” is correct. The rate of change of momentum of an object is directly proportional to the resultant force applied and is in the direction of the resultant force. The resultant force is equal to the rate of change of momentum.
497. What did J B Dunlop invent?
1. Pneumatic rubber tire
2. Car Music System
3. Steering Wheel
4. Diesel Engine
Option “1” is correct. Scottish inventor and veterinary surgeon John Boyd Dunlop developed the pneumatic (air-filled) rubber tire. He was one of the founders of the rubber company that bore his name, Dunlop Pneumatic Tyre Company. In 1888, Dunlop patented his pneumatic tyre.
498. When net torque is zero, __________ will be constant.
1. Force
2. Angular momentum
3. Linear momentum
4. Acceleration
Option “2” is correct. When net torque is zero, angular momentum will be constant.
499. Newton’s first law is also known as _______.
1. Law of friction
2. Law of moments
3. Law of Inertia
4. Law of motion
Option “3” is correct. Newton’s first law of motion is also known as the law of inertia.Newton’s First Law of Motion states, “A body at rest will remain at rest, and a body in motion will remain in motion unless it is acted upon by an external force.”
500. With reference to gravity, what is G called?
1. Gravitational constant
2. Gravitational attraction
3. Gravitational force
4. Acceleration due to gravity
Option “1” is correct. The gravitational constant, symbolized G , is a physical constant that appears in the equation for Newton’s law of gravitation. This is different from ‘g’ which is denotes the acceleration due to gravity.
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