leratio colu 4. Rupal throws a ball upwards at 8ms from a window which is 4m above ground level. (ii) Use your answer to part (i) to find the time the ball hits the ground. (i) Write down an equation for the height hm of the ball above the ground after ts (while it is still in the air). (iii) How fast is the ball moving just before it hits the ground? v) In what way would you expect your answers to parts (ii) and (iii) to change if you were able to take air resistance into account? 5. Nathan hits a tennis ball straight up into the air from a height of 1.25m above the ground. The ball hits the ground after 2.5 seconds. Find (i) the speed Nathan hits the ball (ii) the greatest height above the ground reached by the ball (iii) the speed the ball hits the ground (iv) how high the ball bounces if it loses 0.2 of its speed on hitting the ground. (v) Is your answer to part (i) likely to be an over- or underestimate given that you have ignored air resistance? 6. A ball is dropped from a building of height 30m and at the same instant a stone is thrown vertically upwards that each object moves in a straight line with a constant downward acceleration of magnitude 10ms 2. The stone is thrown with initial speed of 15ms and is hs metres above the ground t seconds later. (i) Draw a diagram of the ball and stone before they collide, marking their positions. (ii) Write down an expression for hs at time t. (iii) Write down an expression for the height hb of the ball at time t. (iv) When do the ball and stone collide? (v) How high above the ground do the ball and stone collide?