Question

My car is accelerating at a rate of 4.0 km/hr/s. The original velocity

was 85 km/hr south. What will the velocity be in 40 seconds?

Answer 1

245 km/h south

Step-by-step explanation:

Since the motion of the car is a uniformly accelerated motion (=constant acceleration), we can use the following suvat equation:

`v=u+at`

where

u is the initial velocity

a is the acceleration

t is the time

v is the final velocity

For the car in this problem we have:

`u=85 km/h` is the initial velocity (taking south as positive direction)

`a=4.0 km/h/s` is the acceleration (the direction is not specified; I assume it is south, so it is also positive)

t = 40 s is the time elapsed

Therefore, the final velocity is

`v=u+at=85+(4.0)(40)=245 km/h`

And since the value is positive, the direction is south.