Question

A runner covers onelap of a circular track 40.0m in diameter in 64.0s .

a. For that lap, what was her average speed?
b. For that lap, what was her average velocity?
c. If she covered the first half-lap in 28.9 s, what was her average speed for thathalf-lap?
d. If she covered the first half-lap in 28.9 s, what were her average velocity for thathalf-lap?

Answer 1

Answer:

(A) 0.625 m /sec

(B) 0 m /sec

(C) 0.692 m /sec

(d) 0.692 m /sec

Explanation:

We have given that a runner covers one lap of track which is 40 m in length in 64 sec

(a) Average speed will be equal to ratio of distance traveled and time taken

So average speed $v=\frac{s}{t}=\frac{40}{64}=0.625m/sec$

(B) Average velocity is the ratio of displacement and time taken

As he completed one lap means comes to his initial position

So displacement will be zero

So average velocity $v=\frac{0}{64}=0m/sec$

(C) Here time is 28.9 sec for half lap

So average speed  $v=\frac{s}{t}=\frac{20}{28.9}=0.6920m/sec$

(D) For half lap displacement will be equal to distance traveled

So average velocity will be equal to v=\frac{s}{t}=\frac{20}{28.9}=0.6920m/sec