Answer:
In collisions between two isolated objects Newton's third law implies that momentum is always conserved. In collisions between two isolated objects momentum is always conserved. Kinetic energy is only conserved in elastic collisions.
Explanation:
Answer: The energy incident on the solar panel during that day is
.
Explanation:
Given: Mass = 250 kg
Initial temperature = 
Final temperature = 
Specific heat capacity = 4200 
Formula used to calculate the energy is as follows.

where,
q = heat energy
m = mass of substance
C = specific heat capacity
= initial temperature
= final temperature
Substitute the values into above formula as follows.

As it is given that water absorbs 25% of the energy incident on the solar panel. Hence, energy incident on the solar panel can be calculated as follows.

Thus, we can conclude that the energy incident on the solar panel during that day is
.
Answer:
Explanation:
(a) The velocity of object is zero when it is at maximum height.
(b) The direction of velocity changes as it starts moving downwards after it reaches the maximum height.
(c) Acceleration due to gravity always acts downwards so its sign remains same.
Answer:
Some of the effects of a dam on the environment includes;
1) Increase in the amount of the greenhouse gases
2) Removal of the natural wetland and ocean carbon sinks
3) Disruption of the sources of nutrients in the ecosystem
4) Destruction of habitats
5) Raising of the sea levels and waste waters
6) Displace villages and communities
7) Dams have a potential to create flood risk
8) Dams lead to increased water loss due to evaporation and transpiration
9) Dams causes earthquakes
Explanation:
Dams are a source of renewable energy and are a means to prevent floods, however, dams can also have detrimental impact on the climate and the environment.
When light moves from a medium with higher refractive index to a medium with lower refractive index, the critical angle is the angle above which there is no refracted ray, and it is given by:

(2)
where

is the refractive index of the second medium and

is the refractive index of the first medium.
We can find the ratio

by using Snell's law:

(1)
where

is the angle of incidence

is the angle of refraction
By using the data of the problem and re-arranging (1), we find

and if we use eq.(2) we can now find the value of the critical angle: