Question

(a) Calculate the height of a cliff if it takes 2. 35 s for a rock to hit the ground when it is thrown straight up from the cliff with an initial velocity of 8. 00 m/s. (b) How long a time would it take to reach the ground if it is thrown straight down with the same speed.

Answer 1

(a) The height of the cliff will be 8.26 meters.

(b) The time would it take to reach the ground will be 0.717 sec.

What is velocity?

The change of displacement with respect to time is defined as the velocity. Velocity is a vector quantity. it is a time-based component.

(a) The height of the cliff will be 8.26 meters.

According to Newton's second equation of motion

$\rm H =ut-\frac{1}{2} gt^2 \\\\ \rm H =8\times 2.35-\frac{1}{2} 9.81 (2.35)^2\\\\\rm H =8.16 \; m$

Hence The height of the cliff will be 8.26 meters.

(b)The time would it take to reach the ground will be 0.717 sec.

We must have the final velocity to find the time so;

$\rm v^2=u^2+2gh\\\\ \rm v^2=8^2+2\times 9.81 \times 8.6 \\\\ \rm v= \sqrt{8^2+2\times 9.81 \times 8.6}\\\\\rm v=15.03 \;m/sec$

According to Newton's third equation of motion ;

$\rm v=u-gt \\\\ \rm t=\frac{v-u}{g} \\\\ \rm t=\frac{15.03-8}{9.81} \\\\ \rm t=0.717 sec.$

Hence the time would it take to reach the ground will be 0.717 sec.

To learn more about the velocity refer to the link ;

brainly.com/question/862972