Question

A ball is thrown upward from edge to a cliff with an initial velocity of 6m/s. How fast is it moving 1/2s later? $\left( {g = 10m/{s^2}} \right)$

Answer 1

Hint: Imagine a ball is thrown upwards from the edge of a cliff at an initial velocity “u = 6m/s”. We know that the ball would be under the effect of gravity and would be having a negative acceleration indicating the direction of the acceleration applied. We have been asked to find out the velocity “v” after 1/2s later. Apply the equation of kinematics and find out the velocity after 1/2s.

Complete step by step answer:
Find out the velocity after 0.5s later:
Apply the formula for kinematics:
$v = u + at$;
Here:
v = Velocity of the ball after 1/2s.
u = Initial velocity of the ball (6m/s).
a = g = Acceleration of the ball due to gravity.
t = Time taken.
 $ \Rightarrow v = 6 + \left( { - 10} \right)\left( {\dfrac{1}{2}} \right)$;
Do the needed mathematical calculation of division in the RHS:
$ \Rightarrow v = 6 + - 5$;
The velocity after 1/2s comes out to be:
$ \Rightarrow v = 1m/s$;

Final Answer: The ball is moving at the velocity of 1m/s, 1/2s later.

Additional Information: Equations used in solving this problem is known as equations of motions or equations of kinematics. These equations of motions were discovered by Galileo and other scientists in the 17th century. They found out that all objects falling through void will have the same constant acceleration. So, a rule named “Merton rule” was used to determine the motion of such objects.

Note: Here the conditions of throwing the ball upwards on the edge of a cliff would be the same as throwing the ball upwards away from the edge of a cliff. In this particular question there would be no difference. The questionnaire had added the scenario just to confuse the student.