Answer :
Given :-
- Constant force, F = 20 N
- Mass of Car = 32 kg
- Initial speed, u = 4 m/s
- Final Speed = 9 m/s
To Find:-
- Duration for which force is appiled
Solution:-
[tex]\green{ \underline { \boxed{ \sf{Force,F= Mass \times Acceleration }}}}[/tex]
So,
[tex] \sf Acceleration,a = \frac{Force}{Mass}[/tex]
[tex] \sf \implies \frac{20}{32} [/tex]
[tex]\implies \frac{5}{8} m/s^2[/tex]
Now,
By first equation of motion -
[tex]\green{ \underline { \boxed{ \sf{v-u=at}}}}[/tex]
So,
[tex]\sf t = \dfrac{v-u}{a} [/tex]
where
- v = final velocity
- u = initial velocity
- a = acceleration
- t = time duration
Putting Values -
[tex]\sf t = \dfrac{9-4}{ \dfrac{5}{8}} [/tex]
[tex]\sf t = \dfrac{5}{ \dfrac{5}{8}} [/tex]
[tex]\sf t = \cancel5 \times \dfrac{8}{\cancel{5}} [/tex]
[tex]\sf t = 8 \:seconds[/tex]
>>>Therefore, Force is applied for 8 seconds.