Answer:
a. 120 W
b. 28.8 N
Explanation:
To a good approximate, the only external force that does work on a cyclist moving on level ground is the force of air resistance. Suppose a cyclist is traveling at 15 km/h on level ground. Assume he is using 480 W of metabolic power.
a. Estimate the amount of power he uses for forward motion.
b. How much force must he exert to overcome the force of air resistance?
(a)
He is 25% efficient, therefore the cyclist will be expending 25% of his power to drive the bicycle forward
Power = efficiency X metabolic power
= 0.25 X 480
= 120 W
(b)
power if force times the velocity
P = Fv
convert 15 km/h to m/s
v = 15 kmph = 4.166 m/s
F = P/v
= 120/4.166
= 28.8 N
definition of terms
power is the rate at which work is done
force is that which changes a body's state of rest or uniform motion in a straight line
velocity is the change in displacement per unit time.
When one object is rubbed against another, static electricity can be created. This is because the rubbing creates a negative charge that is carried by electrons.
Answer:
The error in tapping is ±0.02828 ft.
Explanation:
Given that,
Distance = 200 ft
Standard deviation = ±0.04 ft
Length = 100 ft
We need to calculate the number of observation
Using formula of number of observation

Put the value into the formula


We need to calculate the error in tapping
Using formula of error


Put the value into the formula


Hence, The error in tapping is ±0.02828 ft.
True because on side is heavier than the other
Answer:
Explanation:
a ) wave length of waves in water
= velocity / frequency
= 1482 / (18 x 1000)
= .0823 m
= 8.23 cm
b ) Applying Doppler's effect relation
frequency of reflected wave
= 18000 [ 1482 / (1482 - 4.95 ) ]
= 18000 x 1.003385
= 18061
Difference in frequency= 61 Hz