Question

If a car requires $30$ seconds to accelerate from zero to $90km$ per hour, its average acceleration is, most nearly.

• A. $800m/se{c}^2$
• B. $80m/se{c}^2$
• C. $8m/se{c}^2$
• D. $0.8m/se{c}^2$
• E. $0.08m/se{c}^2$

Answer 1

Answer: (D)

$0.8m/se{c}^2$

Given:

Time taken, $t=30sec$

Initial velocity, $u=0m/s$

Final velocity, $v=90km/h$

$v=90\times \frac{5}{18}=25m/s$

The acceleration of the car is given by:

$a=\frac{v-u}{t}$

Putting the values in the above equation,,

$a=\frac{25-0}{30}=0.833m/s^2$

Therefore, the most nearest option for the average acceleration is $0.8m/s^2$