Question

A body moving with an initial velocity of ms-1 attaina a velocity of 15ms-1 in 3 s. then the displacement is
a. 20 m
b. 3om
c. 40 m
d. 15 m

Answer 1

Correct Question:

A body moving with an initial velocity of 5 m/s attains a velocity of 15m/s in 3 s. then the displacement is

a. 20 m

b. 30 m

c. 40 m

d. 15 m

Anѕwєr :

30 m

Exρlαnαtion :

We have :

Initial velocity of the body ( u = 5 m/s)

Final velocity of the body ( v = 15 m/s)

Time taken (t = 3 s)

Displacement (s= ?)

We can find Displacement by using equations of motion .

Three Equαtions of Motion :

v = u + at ㅤㅤㅤ(i)

s = ut + 1/2 at² ㅤ(ii)

v² - u² = 2as ㅤㅤ(iii)

ㅤㅤㅤㅤㅤㅤ________________ ㅤㅤㅤㅤ

So, for finding Displacement we need to find the acceleration of the body.

Let's find acceleration by using eq(i)

v = u + at

ㅤ>> 15 = 5+ a(3)

ㅤ>> 15 = 5 + 3a

ㅤ>> 15-5 = 3a

ㅤ>> 10 = 3a

>> a = 10/3 m/s²

So, acceleration is 20/3 m/s²

ㅤㅤㅤㅤ__________________

Substituting in eq(ii)

>> s = 5(3) + 1/2 × 10/3 × (3)²

ㅤ>> s = 15 + 5/3 × 9

ㅤㅤ>> s = 15 + 5(3)

ㅤㅤ>> s = 15 + 15

s = 30 m

So, the Displacement is 30 m (b)