C. 10 m/s
You divide 1000 m by 100 s.
1000/100 to find the velocity
Answer: 
Explanation:
Given
Cross-sectional area of wire 
Extension of wire 
Extension in a wire is given by

where, 

for same force, length and material

Divide (i) and (ii)

Answer:
The correct answer is;
Change of phase.
Explanation:
When the physical state in which a substance exists in nature changes to another physical state such as a change from solid state to a liquid stat or from a liquid state to a gaseous state, the substance is said to have undergone a phase change, or phase transformation.
The state of a substance will change, depending on the surrounding temperature and the applied pressure and the energy required for the substance to change its state is known as latent heat.
The observed plateaus are periods the latent heat is absorbed to completely change the phase of the substance.
Answer:
M1 V1 = M1 V2 + M2 V3 conservation of momentum
V2 = (M1 V1 - M2 V3) / M1 where V2 = speed of M1 after impact
V2 = (3 * 9 - 1.5 * 5) / 9 = (27 - 7.5) / 9 = 2.17 m/s
Note: All speeds are in the same direction and have the same sign