Answer: When rubbing a balloon with a wool cloth, it puts negative charges on the balloon. Negative charges attract to positive charges. If a balloon is not rubbed with the wool cloth, it has an equal amount of negative to positive charges, so it will attract to a rubbed balloon.

Explanation:
The acceleration due to gravity g is defined as

and solving for R, we find that

We need the mass M of the planet first and we can do that by noting that the centripetal acceleration
experienced by the satellite is equal to the gravitational force
or

The orbital velocity <em>v</em> is the velocity of the satellite around the planet defined as

where <em>r</em><em> </em>is the radius of the satellite's orbit in meters and <em>T</em> is the period or the time it takes for the satellite to circle the planet in seconds. We can then rewrite Eqn(2) as

Solving for <em>M</em>, we get

Putting this expression back into Eqn(1), we get




Answer:
The voltage across the capacitor is 1.57 V.
Explanation:
Given that,
Number of turns = 10
Diameter = 1.0 cm
Resistance = 0.50 Ω
Capacitor = 1.0μ F
Magnetic field = 1.0 mT
We need to calculate the flux
Using formula of flux

Put the value into the formula


We need to calculate the induced emf
Using formula of induced emf

Put the value into the formula

Put the value of emf from ohm's law





We know that,


We need to calculate the voltage across the capacitor
Using formula of charge


Put the value into the formula


Hence, The voltage across the capacitor is 1.57 V.
B. By vibrations in wires or strings
Answer:
The speed of nitrogen molecule is 1.87 m/s.
Explanation:
Given that,
Pressure = 2 atm
Density = 1.7 grams/liter
Atomic weight = 28 grams
We need to calculate the temperature
Using formula of idea gas




Put the value into the formula


We need to calculate the speed of nitrogen molecule
Using formula of RMS speed



Hence, The speed of nitrogen molecule is 1.87 m/s.