Answer:
A) 7×10⁻⁸ N
Explanation:
r = Distance between the two skaters = 2 m
m₁ = m₂ = Mass of the two skaters = 65 kg
G = Gravitational constant = 6.67 × 10⁻¹¹ m³/kgs²
From Newton's Law of Universal gravity

∴ Force of gravity between the two skaters is 7×10⁻⁸ N
Answer:
The flux of the electric field is 677.6 Nm²/C
Explanation:
Given that,
Area = 18 cm²
Charge = 6.0 nC
We need to calculate the flux of the electric field
Using Gauss's law

Where, q = charge
=permittivity of free space
Put the value into the formula


Hence, The flux of the electric field is 677.6 Nm²/C.
Answer:
Explanation:
In order to find kinetic energy, you need information about the velocity. Speed is the magnitude of the velocity.
Kinetic energy is 1/2mv^2
m being mass
v being velocity
Answer:
(a) the runner's kinetic energy at the given instant is 308 J
(b) the kinetic energy increased by a factor of 4.
Explanation:
Given;
mass of the runner, m = 64.1 kg
speed of the runner, u = 3.10 m/s
(a) the kinetic energy of the runner at this instant is calculated as;

(b) when the runner doubles his speed, his final kinetic energy is calculated as;

the change in the kinetic energy is calculated as;

Thus, the kinetic energy increased by a factor of 4.
The intensity ratio at point A and B will be 81:16.
<u>Explanation:</u>
Sound waves are known to get faded with increase in the distance. This is because, the intensity of the sound is inversely proportional to the square of the distance of the source from the observer. So, if an observer is standing greater distance from the source of the sound, he/she will find difficulty in hearing the sound.
So, as the distance between the source and observer increases, the intensity of the sound wave decreases.

As here two points A and B are located at 4 m and 9 m distance from the source, then the intensity of sound at A and B will be inversely proportional to their respective square of the distance as shown below.

Similarly,

So, the ratio of intensity at point A and B will be

Thus, the intensity ratio at point A and B will be 81:16.