physics

In downhill speed skiing a skier is by both the air drag force on the body and the kinetic frictional force on the skis. Suppose the slope angle is è = 37.5°, the snow is dry snow with a coefficient of kinetic friction ìk = 0.0400, the mass of the skier and equipment is m = 89.5 kg, the cross-sectional area of the (tucked) skier is A = 1.30 m2, the drag coefficient is C = 0.150, and the air density is 1.20 kg/m3.
(a) What is the terminal speed?
m/s

(b) If a skier can vary C by a slight amount dC by adjusting, say, the hand positions, what is the corresponding variation in the terminal speed? (dvt/dC)
m/s

1. 👍
2. 👎
3. 👁
1. Compute the drag force as
(1/2)*C*(air density)*V^2*(Area)

Compute the drag force on the skis with the standard friction coeffient equation.

m g sin A - m g cos A Uk - (1/2) A C (density) V^2 = 0 = Fnet

(a) Write Newton's second law with zero acceleration. The only unknown will be Vt, the terminal speed. Solve for it

(b) Differentiate the law of motion to get dV(C)/dC. You will save a step if you do it impliclitly with respect to C

dFnet/dC = (1/2)A*density*V^2 + (1/2)*A*2V*C*dV/dC*(density)= 0

V^2 + 2 C V*dV/dC = 0

dV/dC = -V/(2C)

2*dV/V = dC/C

1. 👍
2. 👎
2. def class 张徐帅:
def __init__(self, x, y):
return self.x = x
return self.y = y
def ity(self):
return self.x

1. 👍
2. 👎

Similar Questions

1. Physics help needed !

In downhill speed skiing a skier is retarded by both the air drag force on the body and the kinetic frictional force on the skis. Suppose the slope angle is θ = 39.5°, the snow is dry snow with a coefficient of kinetic friction

2. Physic

A 61-kg skier, coasting down a hill that is an angle of 23 to the horizontal, experiences a force of kinetic friction of magnitude 72N. The skier's speed is 3.5m/s near the top of the slope. Determine the speed after the skier has

3. physics

A water-skier is being pulled by a tow rope attached to a boat. As the driver pushes the throttle forward, the skier accelerates. A 71.6-kg water-skier has an initial speed of 5.8 m/s. Later, the speed increases to 11.8 m/s.

4. Physics

A water skier lets go of the tow rope upon leaving the end of a jump ramp at a speed of 17.9 m/s. As the drawing indicates, the skier has a speed of 11.1 m/s at the highest point of the jump. Ignoring air resistance, determine the

1. algebra1

During on Alpine skiing event the times of four Scears were listed below time is measured in seconds skier a= 114.36 skier b=14.40 skier c=114.48 skierD =114.44 If the stopwatch used was only accurate to the 10th of a second which

2. Physics

A Ford Focus with a cross-sectional area of 3.00m^2 is driving on a highway at a speed of 88.0 km/hr, then accelerates to 113 km/hr to pass another car. How much more force does the motor have to supply to overcome air resistance

3. Physics

The drawing shows an extreme skier at three locations on a ski run a) a straight section,b)a circular section and c)an airborn phase in which the skier is in free fall .At the right of the drawing are four possible directions for

4. Physics

A 58 kg skier is coasting down a 250 slope. Near the top of the slope, her speed is 3.6 m/s. She accelerates down the slope because of the gravitational force, even though a kinetic frictional force of magnitude 71 N opposes her

1. Physics

A 10.0-kg object experiences a drag force due to air resistance. The magnitude of this drag force depends on its speed, and obeys the equation Fdrag =(12.0 N-s/m)v + (4.00 N-s2/m2)v2. (a) What is the terminal speed of this object

2. Physics

A 75.0-kg cross-country skier is climbing a 3.0o slope at a constant speed of 2.00 m/s and encounters air resistance of 25.0 N. Find his power output for work done against the gravitational force and air resistance. (b) What

3. Physics help

A 75.0 kg novice skier is going down a hill with several secondary hills. Ignore frictional effects and assume the skier does not push off or slow himself down. If the initial hill is 38.7 m above the chalet level: (8 marks) a)

4. Physics

Calculate the speed a spherical rain drop would achieve falling from 5.00 km (a) in the absence of air drag (b) with air drag. Take the size across of the drop to be 4 mm, the density to be 1.00×103 kg/m3 , and the surface area