Question

A man is driving his 1100 kg car at 36 km/h on a straight freeway. After accelerating for 30 seconds, the car

Answer 1

Answer:

W = 439998 J = 439.99 KJ

Explanation:

First, we will calculate the acceleration of the car by using the first equation of motion:

$v_f = v_i + at\\\\a = \frac{v_f-v_i}{t}$

where,

a = acceleration = ?

vf = final speed = $108(\frac{km}{h})(\frac{1000\ m}{1\ km})(\frac{1\ h}{3600\ s})$ = 30 m/s

vi = initial speed = $36(\frac{km}{h})(\frac{1000\ m}{1\ km})(\frac{1\ h}{3600\ s})$ = 10 m/s

t = time = 30 s

Therefore,

$a = \frac{30\ m/s - 10\ m/s}{30\ s}$

a = 0.67 m/s²

Now, we will calculate the force applied by the engine:

F = ma

where,

F = force = ?

m = mass = 1100 kg

Therefore,

F = (1100 kg)(0.67 m/s²)

F = 733.3 N

Now, we will calculate the distance covered by the car by using the second equation of motion:

$s = v_it+\frac{1}{2}at^2\\\\s = (10\ m/s)(30\ s)+\frac{1}{2} (0.67\ m/s^2)(30\ s)^2$

s = 600 m

Now, the work done (W) by engine can be calculated as follows:

W = Fs

W = (733.3 N)(600 m)

W = 439998 J = 439.99 KJ