Answer:

Explanation:
Aceleration is a change on the velocity of the object in a given time.
For this case: the initial velocity is

and the final velocity is :

so, the change in velocity is:

and the change in time , according to the problem:

So, the aceleration is:

Answer: His average speed in mph over the last 400 m is 7.7 m/s.
Explanation:
Given: Hicham El Guerrouj of Morocco holds the world record in the 1500 m running race. He ran the final 400 m in a time of 51.9 s.
We know that , speed = 
Here , distance = 400m and time = 51.9 s
Then, speed = 
Hence, his average speed in mph over the last 400 m is 7.7 m/s.
Answer:
The radius of the curve that Car 2 travels on is 380 meters.
Explanation:
Speed of car 1, 
Radius of the circular arc, 
Car 2 has twice the speed of Car 1, 
We need to find the radius of the curve that Car 2 travels on have to be in order for both cars to have the same centripetal acceleration. We know that the centripetal acceleration is given by :

According to given condition,


On solving we get :

So, the radius of the curve that Car 2 travels on is 380 meters. Hence, this is the required solution.