Answer:
Mass of bike = 38 kg.
Explanation:
Kinetic energy is given by the expression,
, where m is the mass and v is the velocity.
Here speed of child riding bike = 6 m/s
Mass of child = 30 kg
Total kinetic energy = 1224 J
Let the mass of bike be, m kg
So, total mass of child and bike = (m + 30) kg
Substituting,

So, mass of bike = 38 kg.
Answer:
E. The ocean gains more entropy than the iron loses.
Explanation:
When there is a spontaneous process , entropy of the system increases . Here hot iron is losing entropy and ocean is gaining entropy . Net effect will be gain of entropy . That means entropy gained by ocean is more than entropy lost by iron .
Hence option E is correct .
Answer:
Force applied to smaller cross section is
= 82.63 N
Explanation:
As we know

where
signifies the weight of the two chair in a hydraulic-lift system
And
signifies the area of the two respective chairs in a hydraulic-lift system
Given -
N
Square centimeter
Square centimeter
Substituting the given values in above equation, we get -

Force applied to smaller cross section is
= 82.63 N
When light hits the boundary between two different materials, it can undergo both reflection and refraction.
Reflection is the change in the direction of the
wave that strikes the boundary between two materials.<span> It involves a change in the direction of waves when they clash with an obstacle.
Refraction involves the change in the direction of waves as they move from one medium to </span><span><span>another followed</span></span><span> by a change in speed and wavelength (this second medium should have different permitivity for the light to change its initial properties.)</span>
I don’t know what the angle is in your diagram so I used the angle from the vertical.