Question

2.
Four pairs of initial and final positions of a body along an x axis are given. Which pa
gives a positive displacement of the body?
(a) -10 m, +15 m
(b) -5 m, -12 m
(c) 2 m, 5 m
(d) 2 m, 1m​

Answer 1

Given:

Four pairs of initial and final positions of a body along an x axis are given:

(a) -10 m, +15 m

(b) -5 m, -12 m

(c) 2 m, 5 m

(d) 2 m, 1m

To find:

Which pair shows positive displacement ?

Calculation:

Displacement is the shortest length between the starting and stopping point of an object. In other words, we can say that : displacement is the change in position of an object.

Let displacement be d :

1st pair:

$\therefore \: d = \Delta x \\ \implies \: d= 15 - ( - 10) \\ \implies \: d = 15 + 10 \\ \implies \: d = 25 \: m \: \: \: ....(positive)$

2nd pair:

$\therefore \: d = \Delta x \\ \implies \: d= - 12 - ( - 5) \\ \implies \: d = - 12 + 5 \\ \implies \: d = - 7 \: m \: \: \: ....(negative)$

3rd pair:

$\therefore \: d = \Delta x \\ \implies \: d= 5 - 2 \\ \implies \: d = 3\: m \: \: \: ....(positive)$

4th pair:

$\therefore \: d = \Delta x \\ \implies \: d= 1 - 2 \\ \implies \: d = - 1\: m \: \: \: ....(negative)$

So, 1st and 3rd pair shows +ve displacement.