Answer:
160m/s
Explanation:
The speed of a wave is related to its frequency and wavelength, according to this equation:
v=f ×λ
Given parameters:
Displacement = 8km
Velocity = 3.8km/h
Unknown:
time = ?
Solution:
Velocity is displacement divided by time.
Velocity =
Displacement = velocity x time
Input the parameters:
8 = 3.8 x time
Time =
= 2.1s
The time taken is 2.1s
Explanation:
It is given that The Moon's center is 3.9x10⁸ m from Earth's center. The moon 1.5x10⁸ km from the Sun's center. We need to find the ratio of the gravitational forces exerted by Earth and the Sun on the Moon.
The gravitational force is given by :

It means 
So,

r₁ = 3.9x10⁸ km
r₂= 1.5x10⁸ km
So,

Hence, the ratio of the gravitational forces exerted by Earth and the Sun on the Moon is 5:13.
Answer:
1.9 MPa
Explanation:
Mass of person = 81 kg
Mass of chair = 3.8 kg
Diameter of contact point = 1.2 cm = D
Radius of contact point = 1.2/2 = 0.6 cm
Total mass of chair and person = 81 + 3.8 = 84.8 kg = M
Acceleration due to gravity = 9.81 m/s²
Force acting on the floor
<em>F = Mg</em>
<em>⇒F = 84.8×9.81</em>
<em>⇒F = 831.888 N</em>
Area of the contact point
<em>A = πR²</em>
<em>⇒A = π0.006²</em>
<em>⇒A = π0.000036 m²</em>
Area of the four points is
<em>4A = 0.000144π m²</em>
Pressure

Pressure exerted on the floor by each leg of the chair is 1.9 MPa