Solved Examples

Q.1) How much net force is required to accelerate a 1000 kg car at 4.00 m/s²?

Solution:

Given,

• a = 4.00 m/s²
• m = 1000 kg

Therefore, 

F = ma

= 1000 × 4

= 4000 N

Q.2) Aimee has a toy car mass of 2 kg. How much force should she apply to the car so that it should travel with the acceleration of 8 m/s²?

Solution:

Known,

• m (Mass of toy car) = 2 Kg,
• a (Acceleration) = 8m/s2,

F is Force to be applied by Aimmee = m × a

= 2 Kg × 8 m/s2 = 16 Kgm/s2  = 16 N.

Q.3) A hammer having a mass of 1 kg going with a speed of 6 m/s hits a wall and comes to rest in 0.1 sec. Compute the obstacle force that makes the hammer stop.

Solution:

Given,

• Mass of Hammer, m = 1 kg
• Initial Velocity, u = 6 m/s
• Final Velocity, v = 0 m/s
• Time Taken, t = 0.1 s

The acceleration is: a = (v – u)/t

Therefore, a =  -60 m/s2[-ve sign indicates retardation]

Thus, the retarding Force, F = ma = 1 × 60 = 60 N