Answer:
cold air is more dense than warm water so it sinks to the bottom of the pool
First, we get the difference between the kinetic energies such that,
difference = (220J - 120J)
difference = 100 J
The difference in kinetic energy is the equivalent of the potential energy which is calculated through the equation,
PE = mgh
To calculate for the height, we derive the equation in a form,
h = PE/mg
The product of the mass and acceleration due to gravity is the weight.
h = (100 J) / (5 N)
h = 20 m
<em>Hence, the answer is 20 m. </em>
Fortunately, 'force' is a vector. So if you know the strength and direction
of each force, you can easily addum up and find the 'resultant' (net) force.
When we talk in vectors, one newton forward is the negative of
one newton backward. Hold that thought, while I slog through
the complete solution of the problem.
(100 N forward) plus (50 N backward)
= (100 N forward) minus (50 N forward)
= 50 N forward .
That's it.
Is there any part of the solution that's not clear ?
Explanation:
It is given that,
Mass of the car 1, 
Initial speed of car 1, 
(east)
Mass of the car 2, 
Initial speed of car 2, 
(north)
(b) As the cars stick together. It is a case of inelastic collision. Let V is the common speed after the collision. Using the conservation of momentum as :
The magnitude of speed,
V = 12.22 m/s
(b) Let 
is the direction the wreckage move just after the collision. It is given by :
Hence, this is the required solution.
The speed of the ball is always zero and the acceleration is always -g when it reaches the top of its motion. This is because when the ball is free, only gravity acts on it which is always downwards, hence g is the net acceleration and it is always negative. However the velocity does not direction change instantly, negative acceleration first slows down the ball with a positive velocity, until that point the ball keeps moving up, then the ball velocity becomes zero just before changing direction and becoming negative after which the ball will now go down along gravity. Hence the ball velocity is zero at the top (neither going up nor down). Mathematically this can be seen as velocity is the integration of acceleration.
