At stp (standard temperature and pressure), the temperature is T=0 C=273 K and the pressure is p=1.00 atm. So we can use the ideal gas law to find the number of moles of helium:

where p is the pressure (1.00 atm), V the volume (20.0 L), n the number of moles, T the temperature (273 K) and

the gas constant. Using the numbers and re-arranging the formula, we can calculate n:
Answer:
The answer is "telescopes".
Explanation:
Throughout ancient times, astronomical observatories have indeed been available, and so many historical locations were reserved for astronomical observations. All contemporary astronomers lacked within those older telescopes were lenses until 1610. A telescope is indeed an instrument used to view far-off objects. Telescopes often are being used to look at planets and stars.
Answer:
In physics and chemistry, the law of conservation of energy states that the total energy of an isolated system remains constant; it is said to be conserved over time. ... For instance, chemical energy is converted to kinetic energy when a stick of dynamite explodes.
Part a)
Magnitude of electric field is given by force per unit charge



Part b)
Electrostatic force on the proton is given as
F = qE


PART C)
Gravitational force is given by



PART d)
Ratio of electric force to weight


To solve this problem we will apply the concepts related to the conservation of momentum. That is, the final momentum must be the same final momentum. And in each state, the momentum will be the sum of the product between the mass and the velocity of each object, then


Here,
= Mass of each object
= Initial velocity of each object
= Final velocity of each object
When they position the final velocities of the bodies it is the same and the car is stationary then,

Rearranging to find the final velocity



The expression for the impulse received by the first car is


Replacing,


The negative sign show the opposite direction.