Answer:
60m/s
Explanation:
We are given that
Speed of car after 5 sec, v=40m/s
Acceleration ,a=[tex]-4m/s^2[/tex]
We have to find the initial speed of car.
We know that
Acceleration, a=[tex]\frac{v-u}{t}[/tex]
Where v=Final speed
u=Initial speed
Using the formula
[tex]-4=\frac{40-u}{5}[/tex]
[tex]-4\times 5=40-u[/tex]
[tex]-20=40-u[/tex]
[tex]u=40+20[/tex]
[tex]u=60[/tex]
Hence, initial speed of car=60m/s
