From the top of a cliff of height , Stone P is projected horizontally with speed

PHYSICS · Multi-part · A Level · Physics · Mechanics and materials · Mechanics and materials

Problem

From the top of a cliff of height

h

, Stone P is projected horizontally with speed

u

. After a time delay

\tau

, Stone Q is dropped from rest from the same point. Air resistance is negligible. Use the symbols

h

u

g

and

\tau

where necessary, and take

g = 9.8\,\text{m s}^{-2}

for numerical calculation. (i) Derive the condition on

\tau

for the two stones to reach the ground simultaneously. (ii) If

h = 45\,\text{m}

and

u = 18\,\text{m s}^{-1}

, calculate the numerical value of

\tau

. (iii) For the data in part (ii), find the horizontal separation between the points where Stones P and Q strike the ground.