Answer:
In crash one, because the pink soccer ball had more mass, so it would have a stronger force.
20/.25 is 80, so the car will travel 80 minutes.
Answer:
the final potential energy of this system is 3U0/10
Explanation:
We are given
charge at left end and another test charge at point p
Potential energy is given by =
where k is electrostatics constant = 
Q1 = first charge , Q2= test charge
R= distance between charges
potential at point p
U0 = k*Q1*Q2 /3 ⇒ kq1q2 = 3U0 ..............1
now the test charge moves to point R
using Pytahgoreou theorem
R(distance) =
= 10
New Potential energy
U1 = kq1*q2 / 10
substituting kq1q2 = 3U0 from 1
U1 = 3U0/10
So this is the final potential energy of this system.
B- lack of control.
the scientists did not have a proper control group.