A car increases its speed from 39 km/hr to 75 km/hr in 10 seconds. Its

1.	A car increases its speed from 39 km/hr to 75 km/hr in 10 seconds. Its acceleration is a) 3 m/s2 b) 0.8 m/s 2 c) 1 m/s2 d) 8 m/s2
Answer» Given : Initial velocity of the car = 39 km/hr final velocity of the car = 75km/hr Time taken = 10 sec To find : The acceleration of the car Solution : FIRSTLY we have to convert km/hr to m/s we KNOW that, » 1km/hr = 5/18km/hr » 39km/hr = 39 × 5/18 = 10.8 m/s » 75km/hr = 75 × 5/18 = 20.8 m/s Accerlation is the rate of CHANGE of velocity. It is a vector quantity having both MAGNITUDE as well as direction. SI unit of acceleration is metre per second square. As we are provided with initial velocity, final velocity and time we can use first equation of kinematics that is, v = u + at v denotes final velocity u denotes initial velocity a denotes acceleration t denotes time taken by substituting all the given values in the formula, ➝ v = u + at ➝ 20.8 = 10.8 + a(10) ➝ 20.8 - 10.8 = 10a ➝ a = 10/10 ➝ a = 1m/s² Thus, the acceleration of the car is 1m/s². $\:$

A car increases its speed from 39 km/hr to 75 km/hr in 10 seconds. Its acceleration is a) 3 m/s2 b) 0.8 m/s 2 c) 1 m/s2 d) 8 m/s2

Answer»

Initial velocity of the car = 39 km/hr

final velocity of the car = 75km/hr

Time taken = 10 sec

The acceleration of the car

FIRSTLY we have to convert km/hr to m/s

we KNOW that,

» 1km/hr = 5/18km/hr

» 39km/hr = 39 × 5/18 = 10.8 m/s

» 75km/hr = 75 × 5/18 = 20.8 m/s

Accerlation is the rate of CHANGE of velocity.

As we are provided with initial velocity, final velocity and time we can use first equation of kinematics that is,

v = u + at

by substituting all the given values in the formula,

➝ v = u + at

➝ 20.8 = 10.8 + a(10)

➝ 20.8 - 10.8 = 10a

➝ a = 10/10

➝ a = 1m/s²

Thus, the acceleration of the car is 1m/s².

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