It's harder to block sound because sound waves and transverse waves, causing the sound to bounce off objects. This isn't the same with light. Hope that helps.
Answer:
Efficiency = 71%
Explanation:
Given the following data:
Output energy = 250 Joules
Input energy = 350 Joules
To find efficiency;
Substituting into the equation, we have;

Efficiency = 71.43 ≈ 71%
Therefore, the efficiency of the candle is 71 percent.
Answer:
V = 20 m/s
Explanation:
Given the following data;
Mass = 80kg
Kinetic energy = 16,000 joules
To find the velocity;
Kinetic energy can be defined as an energy possessed by an object or body due to its motion.
Mathematically, kinetic energy is given by the formula;

Where;
K.E represents kinetic energy measured in Joules.
M represents mass measured in kilograms.
V represents velocity measured in metres per seconds square.
Substituting into the formula, we have;
16000 = ½*80*V²
16000 = 40V²
V² = 16000/40
V² = 400
Taking the square root of both sides, we have;
V = 20 m/s
The answer is constant acceleration.