Shawn and his bike have a total mass of
50.9 kg. shawn rides his bike 0.88 km in
16.3 min at a constant velocity.
the acceleration of gravity is 9.8 m/s2.
what is shawn's kinetic energy?
answer in units of j.

Shawn's kinetic energy is 20.6 J

Explanation:

We know that kinetic energy is given by the formula

We are given mass(m) = 50.9kg and

distance ridden by bike = 0.88km which is equal to 880m and

time taken = 16.3 min which is equal to 16.3*60 seconds = 978seconds

Given velocity is constant which is

(v)=

=

= 0.899

Substituting the values we get kinetic energy (k) =

, k = 20.60 kg

as 1J = 1 kg

So, k = 20.60 kg = 20.6 J

see the picture for the vector

the magnitude of the vector by pythagorean theorem

r = √( (-10)^2 + (3)^2 ) = √109

magnitude = √109 units

the direction angle between vector and x-axis is

tan^(-1)(3/10) = 16.699

so the direction is approximately 16.7 degrees north of west

speed of light in vacuum is 300,000 km/s

speed of light in other mediums is given by the expression v = c/n, where c is the speed of light in vacuum and n is the refractive index of medium.

for the first medium v = 200,000 km/s

  so, refractive index of medium = 300000/200000 = 1.5

    1.5 refractive index is usually for glass. so first medium is glass.

for the second medium v = 250,00 km/s

so, refractive index of medium = 300000/250000 = 1.2

    1.2 refractive index is usually for water. so second medium is water.

for the third medium v = 0 km/s

so, refractive index of medium = 300000/0 = ∞

    ∞ refractive index is usually for opaque mediums. so third medium is opaque medium.