A truck moving at a constant speed of 22 m/s passes a slow moving car. The instant the truck passes the car, the car begins to accelerate at a constant rate of 1.2 m/s^2 and passes the truck in 513 m.

Question

What was the speed of the car (in meters/second) when it was first passed by the truck?

Answer 1

Jesse

Let's say s=0 where the truck passes the car.

It will take t = 513/22 s for the truck to move the 513 m until the point that they meet.

Considering the car,

s = ut + 0.5 a t²

s = 513 m

u we need to find

t = (513/22)

a = 1.2 m/s/s (given)

you can just solve this equation for u - I get u = 8.009090909 m/s.

As our data has 2 or 3 significant figures you should quote the answer to 2 significant figures (the minimum of 2 and 3) ie 8.0 m/s.

Mike

Answer 2