Atypical value for the coefficent of quadratic air resistance on a cyclist is around c=0.20 n/m(m/s)2. assuming thath the total mass (cyclist plust cycle) is m = 80 kg and that at t = 0 the cyclist has an intial speed v=20m/s (abouit 45 mi/h) and starts to coast to a stop under the influence of air resistance, find the characteristic time τ=m/cvo. how long will it take him to slow to 15 m/s? what about 10 m/s? and 5 m/s? (below about 5 m/s, it is certainly not reasonable to ignore friction, so there is no point pursuing this calculation to lower speeds.)

Characteristic time τ=20 s

When V = 15 m/s

t = 6.66 s

When V = 10 m/s

t = 20 s

When V = 5 m/s

t = 60 s

Explanation:

Given that

c=0.20 N/m(m/s)2

m = 80 kg

Vo=20m/s

Characteristic time τ=m/cvo.

Characteristic time τ=20 s

We know that velocity after t time given as follows

When V = 15 m/s

t = 6.66 s

When V = 10 m/s

t = 20 s

When V = 5 m/s

t = 60 s

answer: 802.3 kilo joules of energy represents 191.75 kilo calorie of energy.

explanation:

energy released during combustion of one mole methane = 802.3 kilo joules

if 1 kilo joule = 0.239006   kilo calorie

then ,802.3 kilo joule will be = 802.30.239006 kilo calorie

802.3 kilo joule = 191.75 kilo calorie

hence, the energy in kilo calorie is 191.75 kilo calorie.