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Formula:

acceleration= velocity final-velocity initial/time

1- An airplane starts at rest and accelerates down the runway for 20 s. At the end of the runway, its velocity is 80 m/s north. What is its acceleration?

2- A cyclist starts at rest and accelerates at 0.5 m/s^2 south for 20 s. What is the cyclist's final velocity?

Verified Answer :

AL2006

According to the formula you have given us to work with . . .

1). The airplane's acceleration is

(80 m/s north - zero) / (20 sec) = 4 m/sec^2 north

2).  For the cyclist:

                                          (V-final - zero) / 20sec = 0.5 m/s^2 south

Multiply each side by 20s :  V-final = 0.5 m/s^2 south x (20sec) = 

                                                                                         10 m/s south

Acceleration is the rate of change of velocity

when velocity increases its acceleration

and when the velocity decreases its called decelaration

the formula to calculate acceleration is as follows

\(a = \frac{v-u}{t}\)

where

a - acceleration

v - final velocity

u - initial velocity

t - time taken


1. airplane starting at rest means initial velocity - 0 m/s

final velocity - 80 m/s

time - 20 s

substituting the values in the equation

a = (80 m/s - 0 m/s) / 20 s = 80 / 20 = 4 m/s²

the acceleration is 4 m/s² north


2. cyclist starts at rest so initial velocity - 0 m/s

time - 20 s

acceleration - 0.5 m/s²

substituting values in the equation

0.5 m/s² = (v - 0 m/s)/ 20 s

0.5 = v / 20 s

v = 0.5 x 20 = 10 m/s


final velocity is 10 m/s south

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