How Much Force is Needed to Climb a Hill at Constant Speed with Air Resistance?

In summary, the question is asking how much force must be applied to climb a hill at a steady speed with the same air resistance as coasting down the hill. The attempt at a solution involves drawing a free body diagram and using the equations F=ma and sum of forces in the x and y direction to solve for the force of air resistance and net force. The key is to use the steady speed of the downhill case to figure out the magnitude of the air resistance, and then apply that to the uphill case.
  • #1
BMWPower06
92
0

Homework Statement


If a bicyclist of mass 68.0 kg (including the bicycle) can coast down a 6.90 degree hill at a steady speed of 5.80 km/hr because of air resistance, how much force must be applied to climb the hill at the same speed (and the same air resistance)?


Homework Equations


The air resistance equations don't seem to apply.

F=MA as always


The Attempt at a Solution


I drew the FBD, tried to sum the forces and got:
The sum of forces in x= mgsino-Fa (force of air resistance)= ma
Sum of forces in y= N-mgcoso=0

Can anyone help me out?
Thanks
 
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  • #2
BMWPower06 said:

Homework Statement


If a bicyclist of mass 68.0 kg (including the bicycle) can coast down a 6.90 degree hill at a steady speed of 5.80 km/hr because of air resistance, how much force must be applied to climb the hill at the same speed (and the same air resistance)?


Homework Equations


The air resistance equations don't seem to apply.

F=MA as always


The Attempt at a Solution


I drew the FBD, tried to sum the forces and got:
The sum of forces in x= mgsino-Fa (force of air resistance)= ma
Sum of forces in y= N-mgcoso=0

Can anyone help me out?
Thanks
What is the value of the acceleration in the x direction along the incline, if the bicyclist is moving at steady speed?
 
  • #3
Use the data provided in the downhill case to figure out the magnitude of the air resistance. Then apply that to the uphill case.
 
  • #4
Doc Al said:
Use the data provided in the downhill case to figure out the magnitude of the air resistance. Then apply that to the uphill case.

im confused as to which formula i use for air resistance.
 
  • #5
You won't calculate the air resistance directly; instead, you'll deduce it from the fact that the bicyclist moves at a steady speed. What does that tell you about the net force on him?
 

Related to How Much Force is Needed to Climb a Hill at Constant Speed with Air Resistance?

1. What is force?

Force is a push or pull that causes an object to accelerate or change its motion.

2. What is air resistance?

Air resistance is the force that opposes the motion of an object as it moves through the air.

3. How does air resistance affect objects?

Air resistance can slow down the motion of an object by reducing its speed and making it more difficult to move.

4. What factors affect the amount of air resistance an object experiences?

The amount of air resistance an object experiences depends on its shape, size, and speed. Objects with a larger surface area, such as a parachute, experience more air resistance than objects with a smaller surface area, such as a bullet. Additionally, objects that are moving faster will experience more air resistance than objects that are moving slower.

5. How can we reduce the effects of air resistance on an object?

To reduce the effects of air resistance on an object, we can make the object more streamlined or aerodynamic. This means reducing its surface area and shaping it in a way that allows air to flow smoothly around it. Additionally, we can also decrease the speed of the object to reduce the amount of air resistance it experiences.

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