Here are the missing questions:
(a) How fast is the skier moving when she gets to the bottom of the hill?
(b) How much internal energy was generated in crossing the rough patch?
Part A
The initial kinetic energy of the skier is:

Part of this energy is then used to do work against the force of friction. Force of friction on the horizontal surface can be calculated using following formula:

The work is simply the force times the length:

So when the skier passes over the rough patch its energy is:

When the skier is going down the skill gravitational potential energy is transformed into the kinetic energy:

So the final energy of the skier is:

This energy is the kinetic energy of the skier:
Part B
We know that skier lost some of its kinetic energy when crossing over the rough patch. This energy is equal to the work done by the skier against the force of friction.
C) During chemical reaction, total mass remains the same.
This is because due to the law of conservation of mass, stating that in a chemical reaction, neither mass will be created nor destroyed. So, the total mass will not change when chemical reactions occur.
Answer:
A curved mirror is a mirror with a curved reflecting surface. The surface may be either convex or concave. Most curved mirrors have surfaces that are shaped like part of a sphere, but other shapes are sometimes used in optical devices.
Explanation:
Answer:
A mousetrap makes use of a simple machine called a lever.
Explanation:
In a second-class lever the effort force is at the other end, with the load in the middle. In a third-class lever, the load is at the end and the effort force is between the fulcrum and the load. When you set the mousetrap, you are using a second-class lever. Sorry if I get this wrong. I am in 5th grade! ♥