Question

Status: QUESTION S Acceleration is equivalent to O A the increase in speed O B. the change in speed divided by the change in time. O C. the change in direction divided by the change in time. O D. the change in velocity divided by the change in time. QUESTION 6 Sound travels at 343 m/s on a summer day. If a hiker yells down a cavern and hears his echo 2.35 s later, how far is the bottom of the cavern? C A. 806 m B. 403 m O C. 780 m O D.146 m

Answer 1

5. The answer is D, acceleration is equivalent to change in velocity divided by the change in time.

You might confuse between D and B, but if you consider uniform circular motion you will understand the difference. In circular motion an object has constant speed(no change in speed), but still it has non-zero acceleration because it has changing velocity.

6.

Let $x$ be the length of the cavern. The hiker yell (sound wave) travels distance $x$ to the bottom, then it is reflected back by the bottom surface. The echo (reflected sound wave) travel distance $x$ upwards to the hiker.

Overall the sound wave travelled distance $2x$ in time $2.35s$

$Distance = speed \times time$

$2x = 343m/s \times 2.35s$

$2x = 806.05m$

$x = \frac{806.05m}{2} = 403.025m$

The cavern in 403m deep. Correct option is B.