Option “4” is correct. The motion of an object is said to be translatory if the position of the object is changing with respect to a fixed point or object. All the particles of a body excuting translatory motion move in the same direction traversing parallel paths. Train is an example of Translatory motion.
423. Which one of the following is a vector quantity?
1. Momentum
2. Pressure
3. Energy
4. Work
Option “1” is correct. Momentum is a vector quantity while rest of the options are scalar quantity.
424. If the gravitational force of the earth suddenly disappears, which are of the following will be the correct consequence?
1. The weight of an object will become zero but the mass will remain the same.
2. The mass of the object will become zero but the weight will remain the same.
3. Both the mass and the weight of the object will become zero.
4. The mass of the object will increase.
Option “1” is correct. If the gravitational force of the earth suddenly disappears, then the weight of an object will become zero but the mass will remain the same.
425. Red light signal is used as a danger signal because-
1. Red light is scattered least
2. This is comfortable for eyes
3. It produces least chemical reaction
4. It is least absorbed in air
Option “1” is correct. The red light signal is used as a danger signal because it has the highest wavelength and scattered least.
426. When a running car stops suddenly, the passengers tends to lean forward because of –
1. Centrifugal force
2. Inertia of rest
3. Inertia of motion
4. Gravitation force
Option “3” is correct. When the bus is running, the whole body of the passenger is in the state of motion. When the bus stops suddenly, the lower part of the passengers body which is in contact with the bus, comes to rest. But the passengers upper portion remains in the state of motion due to the inertia of motion. This is the reason for the passenger to lean forward when the bus stops suddenly.
427. If a boy is sitting in a train, which is moving at a constant velocity throws a ball straight up into the air, the ball will –
1. fall in front of him
2. fall behind him
3. fall into hand
4. None of the above
Option “3” is correct. If a boy is sitting in a train, which is moving at a constant velocity throws a ball straight up into the air, the ball will fall into his hand.
428. A person is hurt on kicking a stone due to –
1. Inertia
2. Velocity
3. Reaction
4. Momentum
Option “3” is correct. A person is hurt on kicking a stone due to reaction. Here Newton third law of motion is applied which states that every action has equal and opposite reaction.
429. For a body moving with non-uniform acceleration –
1. Displacement-time graph is linear
2. Displacement-time graph is non-linear
3. Velocity-time graph is non-linear
4. Velocity-time graph is linear
Option “3” is correct. For a body moving with non-uniform acceleration, the velocity -time graph is nonlinear.
430. A parachute descends slowly whereas a stone dropped from the same height falls rapidly, because –
1. Stone is heavier than parachute
2. Special mechanisms are present in parachute
3. A parachute has a larger surface area and air resistance is more
4. None of the above
Option “3” is correct. A parachute descends slowly because it has a larger surfaace area and air resistance is more.
