1. A ball is thrown vertically upwards with a velocity of 49m/s. Calculate a) The maximum height to which it rises b) The total time it takes to return to the surface of the earth. 2. A certain force exerted for 1.2 seconds increases the speed of an object from 1.8m/s to 4.2m/s. Later the same force is applied for 2 seconds. How much does the speed change in 2 seconds? 3. A motorboat starting from rest on a lake accelerates in a straight line at a constant rate of three metres per second square for 8 seconds. How far does the boat travel during this time? 4. a) Why are double tyres provided at the rear wheels of a truck? b) A man at the top of a tower throws an object horizontally whereas he simply drops another. Will these two objects reach the earth at the same time? Why? c) Explain why a dead body floats, with its head immersed in water?