Answer:

Explanation:
According to Coulomb's law, the force of attraction between two point charges,
and
, separated by a distance
is given by

is a constant with a value of
.
When we substitute the values from the question,

This value is negative because it is in a direction towards the positive charge.
The work done in moving the electron from the nucleus is


This is negative because work is done on the electron, not by it.
is the magnitude of the magnetic field made by the current
<u>Explanation:</u>
Given data:

Magnetic field of earth, 
We need to find the magnetic field of wire, 
The compass needle moves toward a direction of magnetic field. The current in wire makes a magnetic field in available space where the compass is on the ground. The vector sum of the Earth's magnetic field and the wire's magnetic field represents the net magnetic field, as shown in the attached drawing, expressing the angle:

By substituting the given values, we get


Answer:
Final velocity of the block = 2.40 m/s east.
Explanation:
Here momentum is conserved.
Initial momentum = Final momentum
Mass of bullet = 0.0140 kg
Consider east as positive.
Initial velocity of bullet = 205 m/s
Mass of Block = 1.8 kg
Initial velocity of block = 0 m/s
Initial momentum = 0.014 x 205 + 1.8 x 0 = 2.87 kg m/s
Final velocity of bullet = -103 m/s
We need to find final velocity of the block( u )
Final momentum = 0.014 x -103+ 1.8 x u = -1.442 + 1.8 u
We have
2.87 = -1.442 + 1.8 u
u = 2.40 m/s
Final velocity of the block = 2.40 m/s east.
Answer:
c = 3.00E108 m/s = 3.00E5 km/s
t = S / v = 3.84E5 / 3.00E5 = 1.28 sec