Answer:
every action has an equal and opposite reaction
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as well.
1. Correct
Explanation
An inclined plane is a flat surface which lie at an angle, Its one end is higher than the other this inclined plane is used as an aid for raising or lowering a load. Staircase also work in similar manner
2. Correct
Explanation
yes all simple machine have a fulcrum
3. Incorrect
Explanation
when we swim that time our arms and legs 'push' the water due to which water displaced in backward direction so her we applied a positive work on the water. According to Newton's Third Law,same magnitude of work is done by water in opposite direction to push us back on our arms and legs. therefore water also does positive work on us.
4. incorrect
Explanation
The force exerted by a machine on an object is input force
5. Incorrect
Explanation
when the input force is greater than the output force that time machine have mechanical advantage of less than 1.
Answer: critical angle, sin^-1 (n2/n1)
Explanation: the angle of incidence at which the retracted ray makes an angle of 90° with the normal is known as the critical angle.
Snell's law defined refraction mathematically as shown below
n1 sin θi = n2 sin θr
n1 = refractive index of the first medium
n2 = refractive index of the second medium
θi = angle of incidence
θr = angle of refraction
When the refrafted ray is perpendicular to the normal, the angle of refraction (θr) is 90° hence making the angle of incidence (θi) the critical angle θc
By substituting these conditions into the Snell's law, we have that
n1 sin θc = n2 sin 90
According to trigonometry, the value of sin 90 is 1, hence we have that
n1 sin θc =n2
sin θc = n2/n1
θc = sin^-1 (n2/n1)
Answer:
1742.24106 revolutions per day
Explanation:
v = Velocity
d = Diameter = 1.1 km
r = Radius = 
g = Acceleration due to gravity = 9.81 m/s²
g = 0.9 g
The centrifugal force will balance the gravitational force


The rotation speed is 1742.24106 revolutions per day
Height is the length by nature so i'll use meter to express it!