Page 1 :
ELEGANT CLASSES, NUMERICALS GRAVITATION PHYSICS, 1. An ball is thrown vertically upwards and rises to a height of 10, m., Calculate, (i) the velocity with which the object was thrown upwards, (ii) the time taken by the object to reach the highest point., 2. What happens to the gravitational force between two objects, when the distance between them is :, (i) doubled?, (ii) halved?, 3. The mass of sun is 2 ✕ 1030 kg and the mass of earth is 6 ✕, 1024 kg. If the average distance between the sun and the earth, be 1.5 ✕ 108 km, calculate the force of gravitation between, them., 4. A piece of stone is thrown vertically upwards. It reaches the, maximum height in 3 seconds. If the acceleration of the stone, be 9.8 m/s2 directed towards the ground, calculate the initial, velocity of the stone with which it is thrown upwards. [29.4m/s], 5. A stone falls from a building and reaches the ground 2.5, seconds later. How high is the building? (g = 9.8 m/s2), [30.625m], 6. A stone is dropped from a height of 20 m., (i) How long will it take to reach the ground?, (ii) What will be its speed when it hits the ground? (g = 10 m/s2), [time = 2 sec, v = 20 m/s], 7. When a cricket ball is thrown vertically upwards, it reaches a, maximum height of 5 metres., (a) What was the initial speed of the ball?, (b) How much time is taken by the ball to reach the highest, point? (g = 10 m s−2)[u=-10m/s, t= (√2 − 1) s]