If a 600 kg racing car crashes into the barrier at 85 m/s and it takes 3 seconds for the car to stop still. What is the amount of force that the car hit with?
Show your solution.
Answers
GIVEN :-
- Initial velocity (u) = 85m/s
- Final velocity (v) = 0m/s (car is stopped)
- Time taken (t) = 3s
- Mass (m) = 600kg
TO FIND :-
- Amount of Force (F) , the car hit with.
SOLUTION :-
By 1st Kinematical equation,
★ v = u + at
We have ,
- u = 85m/s
- v = 0m/s
- t = 3s
Putting values we get,
→ 0 = 85 + a(3)
→ 0 = 85 + 3a
→ -85 = 3a
→ a = [-85/3] m/s²
Hence , acceleration of the car is (-85/3)m/s².
__________________
Now , by 2nd Law of Motion,
★ F = ma
Where ,
- F → Force
- m → Mass
- a → Acceleration
We have ,
m = 600kg , a = [-85/3] m/s²
Putting values,
→ F = 600 × (-85/3)
→ F = 200 × (-85)
→ F = - 17000N (negative sign indicates force is applied in opposite direction of motion)
Hence , car hitted with the force of 17000N or 17kN.
MORE INFORMATION :-
1) 2nd Kinematical equation :
- s = ut + (1/2)at²
2) 3rd Kinematical equation :
- v² = u² + 2as
3) Kinematical equations are only applicable when acceleration is constant.
4) Negative acceleration shows that body is retarded. Force is applied in the opposite side of motion of the object.