We cannot consider something to be work unless
2 answers:
Answer:
When displacement caused by force is zero or force is perpendicular to displacement then we consider there will be no work done
Explanation:
We know that work done is given by , here F is force applied and d is the displacement caused by the force
Now there are two case in which work done will be zero that is, either displacement is zero or that is force and displacement are perpendicular to each other
So when displacement caused by force is zero or force is perpendicular to displacement then we consider there will be no work done
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Answer:
(a) The volume of water is 100 cm³
(b) The volume of the rock is 20 cm³
(c) The density of the rock is 30 g/cm³
Explanation:
The given parameters of the perspex box are;
The area of the base of the box, A = 10 cm²
The initial level of water in the box, h₁ = 10 cm
The mass of the rock placed in the box, m = 600 g
The final level of water in the box, h₂ = 12 cm
(a) The volume of water in the box, 'V', is given as follows;
V = A × h₁
∴ The volume of water in the box, V = 10 cm² × 10 cm = 100 cm³
The volume of water in the box, V = 100 cm³
(b) When the rock is placed in the box the total volume, , is given by the sum of the rock,
, and the water, V, is given as follows;
=
+ V
= A × h₂
∴ = 10 cm² × 12 cm = 120 cm³
The total volume, = 120 cm³
The volume of the rock, =
- V
∴ = 120 cm³ - 100 cm³ = 20 cm³
The volume of the rock, = 20 cm³
(c) The density of the rock, ρ = (Mass of the rock, m)/(The volume of the rock)
∴ The density of the rock, ρ = 600 g/(20 cm³) = 30 g/cm³
Hope this helps you.
Answer:
7532m
Explanation:
Gravity on the surface of the earth with radius R is given by:
Gravity a distance r above the surface:
How big is r if:
You get the following equation:
Solve for r: