If 10% of a 85-kg rock climber's total energy expenditure goes into the gravitational energy change when climbing a 120-m vertical slope, what is the climber's average metabolic rate (in watts) during the climb if it takes her 10 min to complete the climb?

Metabolic rate is 1600 W.

Explanation:

Gravitational energy = mgh

= 80 × 10 × 120

=96000

This gravitational energy accounts for 10% of her total energy.

× E(total energy) = 96000

E = 96000 × 10

= 960000 N

Time required = 10 minutes = 10× 60 seconds

=600 seconds

Metabolic rate =

=  

= 1600 W

the minimum constant speed at which she can catch the train is 2.7 m/s

given:

acceleration = 0.6

time = 4.5 s

to find:

velocity = ?

formula used:

from 1st kinematic equation we get,

v = u + at

u = initial speed of train = 0 m/s

v = final speed of the train

a = acceleration of the train

t = time

solution:

from 1st kinematic equation we get,

v = u + at

u = initial speed of train = 0 m/s

v = final speed of the train

a = acceleration of the train

t = time

v = 0 + (0.6 × 4.5)

v = 2.7 m/s

the minimum constant speed at which she can catch the train is 2.7 m/s