Friday

August 1, 2014

August 1, 2014

Posted by **amy** on Monday, May 18, 2009 at 11:26pm.

You are trying to raise a bicycle wheel of mass x and radius r up over a curb of height h . To do this, you apply a horizontal force .

1. What is the least magnitude of the force that will succeed in raising the wheel onto

the curb when the force is applied at the center of the wheel?

2. What is the least magnitude of the force that will succeed in raising the wheel onto the curb when the force is applied at the top of the wheel?

3. In which case is less force required?

case (a)

case (b)

- college -
**drwls**, Monday, May 18, 2009 at 11:57pm1. Consider the torque (moment) applied to the wheel, as measured about the point where the wheel touches the curb. To make the wheel rise above the curb, the torque due to the force must exceed the torque due to the weight, which equals m g sqrt(R^2-h^2) and is in the opposite direction. There will be no force where the wheel touches the road since the wheel will be rising.

The torque due to the applied force is

F (r-h) when it is applied at the center of the wheel.

I will use m instead of x to represent the mass.

F (r-h) = m g sqrt(r^2-h^2)

sqrt(r^2-h^2) is the horizontal distance from the center of the wheel to the point where the wheel touches the curb. It is the "lever arm" for the torque due to the weight

2. Do this case similarly, but the torque due to the applied force becomes

F(2r-h). This will make the required F less.

**Related Questions**

physics - You are trying to raise a bicycle wheel of mass m and radius R up over...

physics - The moment of inertia of a 0.98 kg bicycle wheel rotating about its ...

physics - A bicycle wheel has a diameter of 57.7 cm and a mass of 2.66 kg. The ...

Physics - I am having trouble with the last portion of this question. If someone...

trigonometry - The sprockets and chain of a bicycle are shown in the figure. The...

physics - A bicycle wheel has a diameter of 64.2 cm and a mass of 1.79 kg. ...

Physics - I am having trouble with the last portion of this question. If someone...

Geometry - The wheel of an adult's bicycle has diameter 26 in. The wheel of a ...

Science - You are holding the axle of a bicycle wheel with radius 30 cm and mass...

12th grade - A bicycle wheel has a radius of 0.330 m and a rim whose mass is 1....