Question

It is 5.50km from your home to the physics lab. As part of your physical fitness program, you could run that distance at 10.0km/hr (which uses up energy at the rate of 700W ), or you could walk it leisurely at 3.00km/hr (which uses energy at 290W ).
A) Which choice would burn up more energy? running or walking\
B) How much energy (in joules) would it burn?
C) Why is it that the more intense exercise actually burns up less energy than the less intense one?

Answer 1

Answer:

A) Walking would burn up more energy

B) Walking: 1,914,000 J

Running: 1,386,000 J

C) Even though running is more intense and burns energy at higher rate, it burns energy for a much shorter time than walking.

Explanation:

Watt is a unit for power that is equivalent to Joules per second (J/s). Therefore, to figure out the energy burnt up during an activity, first we need to know how long (in seconds) that activity took.

1- Running

V = 10.0 km/h

d = 5.50 km

t = 5.50/10 = 0.55 h = 0.55(h) *60 (min/h) *60(s/min) = 1,980 s

$E = P*t\\E=700*1,980\\E=1,386,000 J$

2- Walking

V = 3.0 km/h

d = 5.50 km

t = 5.50/ = 1.83333 h = 1.83333(h) *60 (min/h) *60(s/min) = 6,600 s

$E = P*t\\E=290*6,600\\E=1,914,000 J$

A) Walking would burn up more energy

B) Walking: 1,914,000 J

Running: 1,386,000 J

C) Even though running is more intense and burns energy at higher rate, it burns energy for a much shorter time than walking.