# Frictional Force on ball rolling down incline

• Alex22
In summary: However, when plotting the work done/friction against the normal force, the line of best fit is negative, which suggests that there is a force acting against the ball that is not accounted for in the equation for rolling friction. This force is not known, but it might be something like air resistance.
Alex22
Hi everyone,

For an experiment I wanted to investigate the forces acting on a ball when rolling down an incline. Basically I have a wooden incline with a photogate at the bottom to measure the velocity of the ball at the bottom of the ramp.

At the top of ramp the sphere has potential energy mgh. When the ball is released (without any initial speed) it rolls down the incline and through the photogate. Seeing as the photogate is not perfectly on floor level there is still some potential energy. Yet the difference in potential energy should be equal to the gain in kinetic energy (linear and rotational) minus any work done?

In the experiment I altered the height of the ramp and measured the velocity. Yet when attempting to plot a graph of the frictional force (work done/distance traveled by ball) against the normal force (cos theta m g ) I get a very weird line of best fit, with a gradient of around -0.5. If the key force is rolling friction we would expect a positive gradient seeing as the frictional force is normal force multiplied by the coefficient of rolling friction.

Is there some error in my method, some principle I oversaw or are the forces so negligible?

Thanks!

Alex

Do you mean the kinetic energy exceeds the initial potential energy?

Not necessarily, its more of a problem trying to figure out the relationship. I'm stuck on what I should graph for the investigation. GPE and Work Done/Friction correlate positively, yet I can't make much sense of the correlation between the normal and frictional force.

Alex22 said:
Not necessarily, its more of a problem trying to figure out the relationship. I'm stuck on what I should graph for the investigation. GPE and Work Done/Friction correlate positively, yet I can't make much sense of the correlation between the normal and frictional force.

Chet

## 1. What is frictional force?

Frictional force is a type of force that acts against the motion of an object, causing it to slow down or stop. It is the result of the interaction between two surfaces in contact with each other.

## 2. How does frictional force affect a ball rolling down an incline?

Frictional force acts in the opposite direction of the ball's motion, causing it to slow down as it rolls down an incline. The steeper the incline, the greater the frictional force and the slower the ball will roll.

## 3. What factors affect the amount of frictional force on a rolling ball?

The amount of frictional force on a rolling ball is affected by the type of surface the ball is rolling on, the weight and shape of the ball, and the angle of the incline. Smooth and flat surfaces will have less frictional force, while rough and uneven surfaces will have more.

## 4. How can frictional force be reduced on a rolling ball?

Frictional force can be reduced on a rolling ball by using a smoother or more slippery surface, such as a ball bearing or a lubricated track. Additionally, reducing the weight of the ball or decreasing the angle of the incline can also decrease the amount of frictional force.

## 5. How does frictional force on a ball rolling down an incline relate to Newton's Laws of Motion?

Frictional force is an example of Newton's First Law of Motion, which states that an object will remain at rest or in motion at a constant velocity unless acted upon by an unbalanced force. In this case, the frictional force acts as an unbalanced force on the rolling ball, causing it to slow down or change direction.

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