Question

A car accelerates uniformly from 18kmh-1 to 36kmh-1 within a distance of 15m.The uniform acceler

ation of the car is

5.0ms-2

1.5ms-2

2.5ms-2

3.0ms-2​

Answer 1

✬ Acceleration = 2.5 m/s² ✬

Explanation:

Given:

• Initial speed of car is 18 km/h.
• Final speed of car is 36 km/h.
• Distance covered is 15 m.

To Find:

• What is the acceleration of car ?

Formula to be used:

• v² = u² + 2as

Solution: First of all change the km/h to m/s. For this multiply by 5/18.

➟ Initial velocity = 18(5/18) = 5 m/s

➟ Final velocity = 36(5/18) = 10 m/s

Now we have

• u = 5 m/s
• v = 10 m/s
• s = 15 m
• a = ?

Put the values on formula

$\implies{\rm }$ v² = u² + 2as

$\implies{\rm }$ 10² = 5² + 2(a)(15)

$\implies{\rm }$ 100 = 25 + 30a

$\implies{\rm }$ 100 – 25 = 30a

$\implies{\rm }$ 75 = 30a

$\implies{\rm }$ 75/30 = a

$\implies{\rm }$ 2.5 = a

Hence, acceleration of car is 2.5 ms-². ( Option C is correct )

Answer 2

Answer:

Acceleration of the car is 2.5 m/s.