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.
Answer:
E. d and O
Explanation:
"Light passing through a single slit forms a diffraction pattern somewhat different from those formed by double slits or diffraction gratings".
According to Huygens’s principle, "for each element of the wavefront in the slit emits wavelets. These are like rays that start out in phase and head in all directions. (Each ray is perpendicular to the wavefront of a wavelet.) Assuming the screen is very far away compared with the size of the slit, rays heading toward a common destination are nearly parallel".
The destructive interference for a single slit is given by:

Where
d is the slit width
is the light's wavelength
is the angle relative to the original direction of the light
m is the order od the minimum
I represent the intensity
When the intensity and the wavelength are incident normally the angular as we can see on the expression above the angular separation just depends of the distance d and the wavelength O.
The term period (symbol: T) describes the time it takes for an object to complete one full cycle of motion on a spring.
The formula for time is: T = 1 / f , where f is the frequency , f= c / λ = wave speed c (m/s) / wavelength λ (m)..
The formula describes that as the frequency of a wave increases, the time period of the wave decreases.
When boat is sunk into the liquid the net buoyancy on the boat is counterbalanced by weight of the boat
So here weight of the boat = Buoyancy force
let say boat is sunk by distance "h"
now we can say


now by above force balance equation we can write




so boat will sunk by total 5 mm distance