. The brakes of a car are applied to give it an acceleration of -3 m/s2. The car comes to a stop in 5 s. What was its speed when the brakes were applied?
Vfinal=Vinitial+at
solve for Vinitial
The brakes of a car are applied to give it an acceleration of 3-m/s2. The car comes to a stop in 5s. What was its speed when the brakes were applied.
654m/s
To find the speed of the car when the brakes were applied, we can use the kinematic equation:
v = u + at
Where:
v = final velocity (which is zero since the car comes to a stop)
u = initial velocity (which is what we need to find)
a = acceleration (-3 m/s^2)
t = time (5 s)
Rearranging the equation, we have:
u = v - at
Substituting the given values, we have:
u = 0 - (-3 m/s^2)(5 s)
Simplifying the equation, we get:
u = 0 + (3 m/s^2)(5 s)
Calculating the expression, we find:
u = 15 m/s
Therefore, the car's speed when the brakes were applied was 15 m/s.