Question

a powerful motor cycle can accelerate from rest 20m/s in only 4 sec.
a) what is the average
acceleration
b) how far does it travel in the time?

Answer 1

Given that,



Initial velocity of the motorcycle (u) = 0 m/s

Final velocity of the motorcycle (v) = 20 m/s

Time = 4 seconds

To find,

(a) average acceleration = ?

(b) distance covered in 4 seconds = ?

(a) As we know,

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

Average acceleration = $\frac{20 - 0}{4}$

Average acceleration = $\frac{20}{4}$

Average acceleration = $\frac{\cancel{20}}{\cancel{4}}$

$\boxed{\bold{Average\:acceleration = 5\:m/s}}$

Therefore, the average acceleration of the motorcycle is 5 m/s.

(b) By using second equation of motion,

s = ut + $\frac{1}{2}$ at²

s = (0)(4) + $\frac{1}{2}$ (5)(4)²

s = 0 + $\frac{1}{2}$ (5)(16)

s = 0 + $\frac{1}{2}$ (80)

s = $\frac{1}{2}$ (80)

s = $\frac{1}{\cancel{2}} {\cancel(80)}$

$\boxed{\bold{s = 40\:m}}$

Therefore, the distance travelled by motorcycle in 4 seconds is 40 meters.