For a point charge, how does the potential vary with distance from the point charge, r?
a constant
b. r.
c. 1/r.
d.
.
e.
.
Answer:
The correct option is C
Explanation:
Generally for a point charge the electric potential is mathematically represented as

Here we can deduce that the electric potential varies inversely with the distance i.e

So
Answer:
Efficiency
Explanation:
- The amount of mechanical work an engine can do per unit of heat energy it uses is called its efficiency.
- It is also defined as the output divided by the total electrical power consumed.
- In terms of heat, efficiency of engine is given by :

are output heat and input heat respectively.
Hence, the correct option is (d) "efficiency"
It decreases the momentum in the car.
Answer: 2.67 m/s
Explanation:
Given
Mass of block A is 
mass of block B is 
The initial velocity of block A 
the initial velocity of block B is 
After collision velocity of block A is 
Conserving momentum

The momentum of block A after the collision is 
Therefore, there is no change in sign.
I believe the answer is c but I’m not 100% sure