What Force Lifts a Bicycle Wheel Over a Step?

In summary: The conversation discusses how to find the magnitude of the force needed to make a bicycle wheel lose contact with the ground when a horizontal force is applied to its axle. The weight and radius of the wheel are given, and a diagram is recommended to determine the axis and center of mass of the wheel. The goal is to find the torque of each part of the wheel to solve the problem. In summary, the conversation revolves around finding the magnitude of force needed to lift a bicycle wheel off the ground when a horizontal force is applied to its axle, using the given information and a diagram.
  • #1
leezak
43
0
The figure shows a bicycle wheel resting against a small step whose height is h = 0.110 m. The weight and radius of the wheel are W = 29.0 N and r = 0.350 m. A horizontal force F is applied to the axle of the wheel. As the magnitude of F increases, there comes a time when the wheel just begins to rise up and loses contact with the ground. What is the magnitude of the force when this happens?

I drew a diagram, yet I'm not even sure how to start this problem... help please! thanks!
 
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  • #2
leezak said:
The figure shows a bicycle wheel resting against a small step whose height is h = 0.110 m. The weight and radius of the wheel are W = 29.0 N and r = 0.350 m. A horizontal force F is applied to the axle of the wheel. As the magnitude of F increases, there comes a time when the wheel just begins to rise up and loses contact with the ground. What is the magnitude of the force when this happens?
I drew a diagram, yet I'm not even sure how to start this problem... help please! thanks!
The step provides an axis (a line about which the wheel rotates) which divides the wheel into two parts. You have to determine how that axis divides the mass of the wheel. Then is a matter of determining the centre of mass of each part of the wheel to find the torques.

AM
 
  • #3


The bicycle torque problem can be solved using basic principles of mechanics and torque. To begin, we can set up the equation for torque, which is T = F * r * sin(theta), where T is torque, F is the applied force, r is the distance between the point of rotation and the point where the force is applied, and theta is the angle between the force and the lever arm.

In this case, the lever arm is the radius of the wheel (0.350 m) and the angle between the force and the lever arm is 90 degrees, since the force is being applied horizontally. Therefore, the equation becomes T = F * 0.350 m * sin(90 degrees). Since sin(90 degrees) = 1, the equation simplifies to T = 0.350 F.

Next, we need to consider the torque caused by the weight of the wheel. This torque is equal to the weight (W) multiplied by the lever arm (0.110 m). Therefore, the torque due to the weight is T = W * 0.110 m = 29.0 N * 0.110 m = 3.19 Nm.

In order for the wheel to start to rise up and lose contact with the ground, the applied torque (T) must be equal to or greater than the torque due to the weight (3.19 Nm). Therefore, we can set up the following equation:

0.350 F = 3.19 Nm

Solving for F, we get F = 3.19 Nm / 0.350 m = 9.11 N.

Therefore, the magnitude of the force when the wheel just begins to rise up and loses contact with the ground is 9.11 N.
 

FAQ: What Force Lifts a Bicycle Wheel Over a Step?

What is the bicycle torque problem?

The bicycle torque problem is a physics concept that refers to the force applied to the pedals of a bicycle to make it move forward. It is the combination of the rider’s weight, the force applied to the pedals, and the rotation of the pedals that creates torque and propels the bicycle forward.

What factors affect bicycle torque?

The key factors that affect bicycle torque are the rider’s weight, the gear ratio of the bicycle, and the force applied to the pedals. The weight of the rider determines the amount of force that can be applied to the pedals, while the gear ratio and force applied determine the speed and efficiency of the bicycle’s movement.

How does gear selection impact bicycle torque?

Gear selection plays a crucial role in bicycle torque as it affects the amount of force needed to rotate the pedals. A lower gear ratio requires less force to turn the pedals, making it easier to pedal and resulting in a lower torque. On the other hand, a higher gear ratio requires more force to turn the pedals, resulting in a higher torque and faster movement of the bicycle.

How can we maximize bicycle torque?

To maximize bicycle torque, it is essential to find the optimal balance between the rider’s weight, gear ratio, and force applied to the pedals. This can be achieved by adjusting the gear ratio to match the terrain and using proper pedaling techniques, such as pushing and pulling on the pedals simultaneously, to distribute the force evenly and efficiently.

How does bicycle torque affect performance?

Bicycle torque directly affects the performance of the bicycle, as it determines how fast and efficiently the bicycle can move. A higher torque allows for faster acceleration and movement, while a lower torque may result in slower and more strenuous pedaling. Therefore, understanding and optimizing bicycle torque is crucial for improving overall performance on a bicycle.

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