Answer:
The semi truck travels at an initial speed of 69.545 meters per second downwards.
Explanation:
In this exercise we see a case of an entirely inellastic collision between the semi truck and the car, which can be described by the following equation derived from Principle of Linear Momentum Conservation: (We assume that velocity oriented northwards is positive)
(1)
Where:
, 
- Masses of the semi truck and the car, measured in kilograms.
, 
- Initial velocities of the semi truck and the car, measured in meters per second.
- Final speed of the system after collision, measured in meters per second.
If we know that 
, 
, 
and 
, then the initial velocity of the semi truck is:
The semi truck travels at an initial speed of 69.545 meters per second downwards.
So impulse is a change in momentum.
Mass*(final velocity - initial velocity)
I dont think you will be able to find the average force with the given info because you need to know the time it takes for the car to slow down.
Refraction
the fact or phenomenon of light, radio waves, etc. being deflected in passing obliquely through the interface between one medium and another or through a medium of varying density.
Complete Question:
Metal sphere A has a charge of − Q . −Q. An identical metal sphere B has a charge of + 2 Q . +2Q. The magnitude of the electric force on sphere B due to sphere A is F . F. The magnitude of the electric force on sphere A due to sphere B must be:
A. 2F
B. F/4
C. F/2
D. F
E. 4F
Answer:
D.
Explanation:
If both spheres can be treated as point charges, they must obey the Coulomb's law, that can be written as follows (in magnitude):
As it can be seen, this force is proportional to the product of the charges, so it must be the same for both charges.
As this force obeys also the Newton's 3rd Law, we conclude that the magnitude of the electric force on sphere A due to sphere B, must be equal to the the magnitude of the force on the sphere B due to the sphere A, i.e., just F.
