Answer:
a) 3.43 m/s
Explanation:
Due to the law of conservation of momentum, the total momentum of the bullet - rifle system must be conserved.
The total momentum before the bullet is shot is zero, because they are both at rest, so:

Instead the total momentum of the system after the shot is:

where:
m = 0.006 kg is the mass of the bullet
M = 1.4 kg is the mass of the rifle
v = 800 m/s is the velocity of the bullet
V is the recoil velocity of the rifle
The total momentum is conserved, therefore we can write:

Which means:

Solving for V, we can find the recoil velocity of the rifle:

where the negative sign indicates that the velocity is opposite to direction of the bullet: so the recoil speed is
a) 3.43 m/s
Explanation:
The capacitance in two parallel-plate capacitors is:

For air, we have 
For plastic, we have 
Hence:

a) Recall that the potential difference between the plates is the same (
). The electric field is given by:

The potential difference is defined as:

Replacing:

b) The energy is defined as:

So:

When you start sliding the couch, you have to overcome the static friction of the carpeted floor, which is usually very big, especially due to the texture of the carpet. However, as long as you get it moving, you only have to apply the force to overcome the kinetic friction, which is smaller than the static friction.
Believe: 1. The Gimlin/Patterson film
2. Footprints and other evidences
3. Hair samples
4. Native American legends
5. The Bering Land Bridge
6. Discovery of the Modern Gorilla
Answer:

Explanation:
kilo is a prefix that means
of the base unit.