Answer:
92 protons
Explanation:
The mass number is
238
, so the nucleus has <u>238 particles</u> in total, including <u>146 neutrons</u>. So to calculate the number of neutrons we have to subtract: 238 − 146 = 92
Answer:
Gravity varies when the Earth rotates and its mass and density differ based on where you are on the planet. Knowing how gravity affects sea level thus aids geodesists in making more precise calculations. The mean sea level would be higher in parts of the earth where gravitational forces are heavier.
Explanation:

Every object in the universe attracts every other object with a force which is proportional to the product of their masses and inversely proportional to the square of the distance between them. The forces along the line joining the centre of the two objects.
❍ Let us consider two masses m1 and m2 line at a separation distance d. Let the force of attraction between the two objects be F.
According to universal law of gravitation,

Also,

Combining both, We will get

Or, We can write it as,

Where, G is the constant of proportionality and it is called 'Universal Gravitational constant'.
☯️ Hence, derived !!
<u>━━━━━━━━━━━━━━━━━━━━</u>
Answer:
80%
Explanation:
Efficiency = Power output / Power input × 100 %
To calculate efficiency we need to find power output of electric pump.
We can use,
Work done = Energy change
Work done per second = Energy change per second
Work done per second = Power
Therefore, Power = Energy change per second
= Change in potential energy of water per second
=mgh / t
= 200× 10×6 / 10
= 1200 W = 1.2 kW
Now use the first equation to find efficiency,
Efficiency =
× 100%
= 80 %