Physics help needed?

Question

i don't have any example similar to this question in the book so i am not able to understand it.

while driving his sports car at 20.m/s down a four-lane highway, eddie comes up behind a slow-moving dump truck and decides to pass it in the left hand lane. if eddie can accelerate at 5.oom/s2 , how long will it take for him to reach a speed of 30.om/s?

(note s2 is for s with square root)
pls explain me how to do this since i have no similar examples to this in my book.

Answer 1

acceleration is measured in meters/sec/sec, or m/s²

Eddie is going 20 m/s, and he can accelerate at 5 m/s².

20 + 5 t = 30

5 t = 10

t = 2

He must accelerate for 2 seconds to reach a speed of 30 m/s²

Answer 2

That's meters per second SQUARED, not square root. His speed increases by 5 meters per second, every second. At 1 second he's going 5 m/s, and 2 seconds he's going 10 and so on.

If he starts out at 20 m/s, and he must reach 30 m/s, and he can increase his speed by 5 meters per second every second...

(You should be able to figure this out now)

The truck, the number of lanes on the highway, the fact that he's trying to pass, all of this is irrelevant. All that matters is the speed he starts out at, the speed he wants to get to, and how quickly he can accelerate. You need to learn to filter out the unnecessary information.

Answer 3

He need an additional speed of 10 m/s^2. If his rate of acceleration is only 5 m/s^2, (meaning that every second, his speed increases by 5 m/s) then it should take 2 seconds.

Answer 4

since he is accelerating at that rate 5.oom/s2, this means that with each succesive second, he is going 5 m/s faster therefore, in 2 seconds he will be going 10 m/s faster putting him at 30m/s.

Answer 5

Well um.....if I told you isn't that cheating?