Question

Take the acceleration due to gravity as g= 9.81ms-2

A red ball is thrown straight up from the edge of the roof of a building. A green ball is dropped from the same point (t = 1.80s) seconds later.

(a) If the height of the building is (h = 74) m, what is the initial velocity (ured) of the red ball, if both balls are to hit the ground at the same time ?

Now consider the same situation, but let the initial velocity be a known quantity and the height of the building (h) be the unknown. Take your value of t.

(b) Perform a calculation to determine the height of the building which would satisfy the condition that both balls would hit the ground at the same moment, for the following values of ured
(i) 12.0 ms-1 (ii) 19.1 ms-1

(c) for your value of t, if ured is greater than some maximum value umax there is no value of h that allows both balls to strike the ground at the same time.
(i) Determine the value of umax
(ii) There is a physical interpretation of this situation. What is it?

(d) for your value of t, if ured is less than some minimum value umin there is no value of h that allows both balls to strike the ground at the same time.
(i) Determine the value of umin
(ii) There is a physical interpretation of this situation. What is it?

Answer 1

what class is this lesson for?