Question

a car starts from rest and retains the acceleration of 4mls in 20 sec .calculate its final velocity​

Answer 1

Answer:

80m/s in the direction of acceleration.

Explanation:

GIVEN -

initial velocity u= 0 (rest)

acceleration = 4m/s

time = 20s

let final velocity will be v

relation between acceleration and velocity= (v-u)/t

                                                        4 = v -0/20

                                                 4 * 20 = v-0

                                                    v = 80 m/s.

Answer 2

Question :

A car starts from rest and retains the acceleration of 4 m/s² in 20 sec . Calculate it's final velocity.

Given :

• A car starts from rest and acquired an acceleration of 4 m/s² in 20 sec

To find :

• The final velocity of the car

Solution :

From first equation of motion ,

$\large \dag \: \boxed {\rm{v = u + at}}$

Where ,

• v is final velocity of the body
• u is initial velocity of the body
• a is acceleration of the body
• t is time taken

$: \implies \rm \: v - u = at \\ \\ : \implies \rm {\boxed{ \rm{a = \frac{v - u}{t} }}}$

We have ,

• u = 0 m/s ( Since the car has started from rest)
• v = ?
• a = 4 m/s²
• t = 20 sec

By subsituting the values ,

$: \implies \rm 4 = \dfrac{v - 0}{20 \: } \\ \\ : \implies \rm \: 4 \times 20 = v \\ \\ : \implies \rm \: v = 80 \: m {s}^{ - 1}$

∴ The final velocity of the car is 80 m/s