Physics - Study Mode
[#926] The force that keeps a body in a circular motion called
Correct Answer
(A) The centripetal force
Explanation
Solution: A centripetal force is a net force that acts on an object to keep it moving along a circular path.
[#927] It is easier to carry two buckets of water in one hand each, than to carry only one in one hand because
Correct Answer
(C) Centre of gravity and centre of equilibrium fall within the feet
Explanation
Solution: It is easier to carry two buckets of water in one hand each, than to carry only one in one hand because the centre of gravity and centre of equillibrium fall within the feet. The weight is spaced out more evenly on both the sides of the body than it would be if you had to carry in a single bucket.
[#928] The working of a rocket is based on the principle of:
Correct Answer
(A) Conservation of momentum
Explanation
Solution: Rocket works on the principle of conservation of linear momentum.
[#929] A bomb at rest explodes into a large number of tiny fragments. The total momentum of all the fragments
Correct Answer
(A) Is zero
Explanation
Solution: In an explosion, an internal impulse acts in order to propel the parts of a system (often a single object) into a variety of directions. After the explosion, the individual parts of the system (that is often a collection of fragments from the original object) have momentum. If the vector sum of all individual parts of the system could be added together to determine the total momentum after the explosion, then it should be the same as the total momentum before the explosion. Just like in collisions, total system momentum is conserved.
[#930] A man standing at the top of a tower has two spheres A and B. He drops sphere A downwards and throws sphere B horizontally at the same time. Which of the following is correct ?
Correct Answer
(A) Both the spheres will reach the ground simultaneously.
Explanation
Solution: If no air resistance is present, the rate of descent depends only on how far the object has fallen, no matter how heavy the object is. This means that two objects will reach the ground at the same time if they are dropped simultaneously from the same height. This statement follows from the law of conservation of energy.