Answer:
C. A rubber rod and a glass rod charged this way have opposite charges on them.
Explanation:
When a rubber rod is rubbed against cat fur, it acquires a negative charge, it becomes negatively charged.
When you then try to bring two rubber rod's together, they repel because like charges repel.
Meanwhile, when you rub a glass rod against silk, it loses electrons to the silk material and becomes positively charged.
When you bring two positively charged glass rod's together, they repel, because like charges repel.
However, when you bring the rubber rod and a glass rod together, the attract each other because unlike/opposite charges attract.
Answer:
the kinetic energy lost due to friction is 22.5 J
Explanation:
Given;
mass of the block, m = 0.2 kg
initial velocity of the block, u = 25 m/s
final velocity of the block, v = 20 m/s
The kinetic energy lost due to friction is calculated as;

Therefore, the kinetic energy lost due to friction is 22.5 J
Answer:
Newton
Explanation:
The earth attracts every body towards its centre. The force with which the earth attracts any body towards its centre, is called its weight.
It is a vector quantity.
It always acts towards the centre of earth.
The SI unit of Newton.
The net force does not depend on the mass.
We have 12N to the right, and 19N to the left.
The net force is (19.0-12.0)N=7.0N to the left.
Answer:

Explanation:
A differential equation that contain a term with di(t)/dt is in a RL circuit. Here we have

where vr is the voltage in the resistance, vi is the voltage in the inductance and vb is the source voltage. But also we have that

where L is the inductance of the circuit, r is the resistance an i is the current. By replacing we have the differential equation

I hope this is useful for you
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