[lueeewss]

A car is smashed into a wall during Weaverville’s July 4th Destruction Derby. The car is
Going 25 m/s just before it strikes the wall. It comes to a stop 0.8 seconds later. What is the
Average acceleration of the car during the collision?

You are sitting on your bike at rest. Your brother comes running at you from behind at a
Speed of 2 m/s. At the exact moment he passes you, you start up on your bike with an
Acceleration of 2 m/s2.
a. Draw a picture of the situation, defining the starting positions, speeds, etc.
b. At what time t do you have the same speed as your brother?
c. At what time t do you pass your brother?

[Abhimanyu Pudi]

For #1, car's velocity before it strikes the wall is 25 m/s and it does not change during the collision, if the collision is elastic. It cannot be inelastic as we do not know the mass of the wall. It may stay somewhere between elastic and inelastic but without any given coefficient of restitution, we cannot proceed in this way.
So, finally we are left with only the elastic collision where we have details to solve the problem and as I said, velocity of the car remains constant in elastic collision and the average acceleration become zero!!

[Abhimanyu Pudi]

In #2, as for the first part a, I cannot draw any diagram.

b. your initial velocity on bike is zero, acceleration is 2 m/s^2 and you need to gain a velocity of 2 m/s. By first equation of motion,
v=u+at
2=0+2t and so t=1s
c. Find out the time when you reach your brother in distance and that is the answer.