Question

Wilma I. Ball walks at a constant speed of 5.93 m/s along a straight line from point A to point B and then back from B to A at a constant speed of 3.15 m/s.
(a)

What is Wilma's average speed over the entire trip?Wilma I. Ball walks at a constant speed of 4.51 m/s along a straight line from point A to point B and then back from B to A at a constant speed of 3.15 m/s.

(a)

What is Wilma's average speed over the entire trip?

(b)

What is Wilma's average velocity over the entire trip?

Answer 1

Answer:

Case:1 a) average speed $v_{avg}=4.1144\ m.s^{-1}$

Since the body returns to its initial position hence the displacement is zero so velocity is also zero.

CASE: 2 a) average speed $v_{avg}=3.7093\ m.s^{-1}$

Since the body returns to its initial position hence the displacement is zero so velocity is also zero.

Explanation:

Given:

Case: 1

speed of Wilma from point A to B, $v_{ab}=5.93\ m.s^{-1}$

speed of Wilma from point B to A, $v_{ba}=3.15\ m.s^{-1}$

Let the displacement from A to B be x meter.

Then the total displacement = 2x meter

time taken in going from A to B:

$t_{ab}=\frac{x}{5.93}\ s$

time taken in going from B to A:

$t_{ba}=\frac{x}{3.15} \ s$

Wilma's average speed over the entire trip:

$v_{avg}=\frac{2x}{t_{ab}+t_{ba}}$

$v_{avg}=2x\div (\frac{x}{5.93}+\frac{x}{3.15})$

$v_{avg}=4.1144\ m.s^{-1}$

• Since the body returns to its initial position hence the displacement is zero so velocity is also zero.

CASE: 2

speed of Wilma from point A to B, $v_{ab}=4.51\ m.s^{-1}$

speed of Wilma from point B to A, $v_{ba}=3.15\ m.s^{-1}$

Let the displacement from A to B be x meter.

Then the total displacement = 2x meter

time taken in going from A to B:

$t_{ab}=\frac{x}{4.51}\ s$

time taken in going from B to A:

$t_{ba}=\frac{x}{3.15} \ s$

Wilma's average speed over the entire trip:

$v_{avg}=\frac{2x}{t_{ab}+t_{ba}}$

$v_{avg}=2x\div (\frac{x}{4.51}+\frac{x}{3.15})$

$v_{avg}=3.7093\ m.s^{-1}$

• Since the body returns to its initial position hence the displacement is zero so velocity is also zero.