Question

A car of mass 1000Kg is moving with a velocity of 10m/s and is acted upon by a forward force of 1000N due to engine and retarding force of 500N. Calculate the velocity after 10 sec

Answer 1

Answer in the picture

Answer 2

Answer:

Velocity of the car after 10 sec is 15 m/s.

Explanation:

Given,

• Mass of the car = m = 1000 kg
• Initial velocity of the car = u = 10 m/s.
• Forward force acting on the car = F = 1000 N
• Retarding force acting on the car = f = 500 N
• Total time interval = t = 10 sec

According to the question, the forward force accelerates the motion while the retarding force acting on the car deaccelerates the motion of the car. Therefore Net force acting on the car generates an acceleration in the car.

From the Newton's second law,

$\therefore \sum F_{net}\ =\ ma\\\Rightarrow F\ -\ f\ =\ ma\\\Rightarrow a\ =\ \dfrac{F\ -\ f}{m}\\\Rightarrow a\ =\ \drac{1000\ -\ 500}{1000}\\\Rightarrow a\ =\ 0.5\ m/s^2$

Thus the acceleration of the car is 0.5 $m/s^2$

Now Let v be the final velocity of the car after time t = 10 sec

From the kinematics,

$v\ =\ u\ +\ at\\\Rightarrow v\ =\ 10\ +\ 0.5\times 10\\\Rightarrow v\ =\ 15\ m/s.$

Hence the velocity of the car after 10 sec is 15 m/s.