Question

A stone is thrown from a bridge at an angle of ${30}^o$ down with the horizontal with a velocity of $25m/s$. If the stone strikes the water after $2.5$ seconds, then calculate the height of the bridge from the water surface. ($g=9.8m/s^2$)

• A. 0.625 m
• B. 0.5 m
• C. 1 m
• D. 5 m

Answer 1

Answer: (A)

0.625 m

Using the equation, $s=ut+\frac{1}{2}a{t}^2$

$u=25sin{30}^0=12.5m/s$

a= $g=-9.8m/s^2$ (with sign convention)

So, s= 0.625 m