Question

A car accelerates uniformly from 18 km per hour to 36 kilometer per hour in 5 minutes.The acceleration is
a) 5 meter per second square
b) 1 kilometre per second square
c) 216 meter per second square ​
d) 216 kilometre per second square

Answer 1

Answer:

0.0166.....m/s^2

Explanation:

Given :

Initial velocity = 18 km/h (u)

$18 \frac{km}{h} = 18 \times \frac{5}{18} = 5 \: \frac{m}{s}$

Final velocity = 36 km/h (v)

$36 \frac{km}{h} = 36 \times \frac{5}{18} = 10 \: \frac{m}{s}$

Time = 5 minutes (t)

1 minute = 60 seconds

So,

5 minutes = 5×60 seconds

5 minutes = 300 seconds

$acceleration \: = \frac{v - u}{t}$

Substituting the values, we get:

$acceleration \: = \frac{10 - 5}{300}$

$acceleration \: = \: \frac{5}{300}$

$a \: = \frac{1}{60}$

Acceleration = 0.01666....m/s^2

The Acceleration of the car is  equal to 0.0166.... m/s^2

Answer 2

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CORRECT QUESTION :

A car accelerates uniformly from 18 km per hour to 36 kilometer per hour in 5 minutes.

The acceleration is -

a) 5 meter per second square

b) 1 kilometre per second square

c) 216 meter per second square

d) 216 kilometre per second square

SOLUTION :

The above body starts from a uniform velocity. . Hence it's innitial velocity is 18 km / hr = 18 × ( 5 / 18 ) m / s = 5 m / s

Its final Velocity is 36 km / hr = 36 × ( 5 / 18 ) m / s = 10 m / s.

Time = 5 minutes = 300 seconds.

According to the first Equation of Motion -

a = { v - u } / T

Substuting the required Values -

a = { 5 / 300 } m / s ^ 2 = { 1 / 60 } m / s ^ 2 = 0.0166 m / s ^ 2.

=> { 0.001 / 60 } km / s ^ 2 = 0.00166 km / s ^ 2.

Hence none of the given options are correct.