Question

define acceleration. a bus decreases its speed from 90 km/hr to 18 km/hr in 10 s. find the acceleration of the bus.​

Answer 1

Explanation:

Define of acceleration.

• Rate of change of velocity.

Acceleration formula

$\sf \: Acceleration = \frac{Final Velocity -Initial Velocity} {time}$

• inital ( starting) velocity=u
• Final velocity=v
• Acceleration= a

$\sf{ \therefore} \: a = \frac{v - u}{t}$

$\sf \: SI \: unit \: of \: acceleration = m/s²$

Given:

• Initial Velocity (u) = 90 km/hr

• Final Velocity (v) = 18 km/hr

• Time (t) = 10 seconds

To Find :

• Acceleration of the bus

Solution :

First of all let's convert given velocities into m/s

▪ 90km/hr

→ 90 × 5/18

→ 5 × 5

→ 25 m/s

▪ 18km/hr

→ 18 × 5/18

→ 5 m/s

Now,

$\sf★ Acceleration = \frac{Final \: Velocity -Initial \: Velocity}{Time taken}$

$★ \: \sf a = \frac{v - u}{t} \\ \\ \sf ★ \: a = \frac{25 - 5}{10} \\ \\ \sf★ a = \frac{20}{10}$

a =2 m/s²

∴ Acceleration of the bus is 2m/s²

Since the speed of the bus is decreasing, therefore the value of the acceleration is in negative.