Answer:

Explanation:
We must use conservation of linear momentum before and after the collision, 
Before the collision we have:

where these are the masses are initial velocities of both players.
After the collision we have:

since they clong together, acting as one body.
This means we have:

Or:

Which for our values is:

Answer:
19.5°
Explanation:
The energy of the mass must be conserved. The energy is given by:
1) 
where m is the mass, v is the velocity and h is the hight of the mass.
Let the height at the lowest point of the be h=0, the energy of the mass will be:
2) 
The energy when the mass comes to a stop will be:
3) 
Setting equations 2 and 3 equal and solving for height h will give:
4) 
The angle ∅ of the string with the vertical with the mass at the highest point will be given by:
5) 
where l is the lenght of the string.
Combining equations 4 and 5 and solving for ∅:
6) 
Answer:
1. Emma standing on top of mountain
Since she is at the rest position and at some height from the ground so here energy is due to gravitational potential energy
So we have
gravitational potential energy

2. Emma jumping down from mountain top
Due to free fall Emma will start moving with some speed in downwards direction so here we have

motion energy
3. tension in rope at Emma’s lowest position
Due to stretch in the rope here position come to the lowest end and speed comes to zero so whole energy is converted into elastic potential energy

elastic potential energy
4. Emma bouncing back
Due to bouncing back she will again have its kinetic energy with some speed upwards

motion energy
Answer:
A. Repeating an experiment to verify results
Explanation:
A scientific theory may be defined as the theory of science that is a thought out explanation of the observations done in the nature or that happens in the natural world. They are constructed using several scientific methods by observing many facts and hypothesis.
According to the question, repeating of an experiment a number of times and verifying its result may help in improving a scientific theory as if we get the similar result for each experiments, then it confirms the basis of the hypothesis or the facts that are observe in the nature and conclude a scientific theory.