# A man of mass 70kg rides a bicycle of mass 15kg at a steady speed of 4

• Doubell
In summary, the problem involves a man of mass 70kg riding a bicycle of mass 15kg at a steady speed of 4 ms-1 up a road with a slope of 1.0 m for every 20m of its length. The cyclist is facing a constant resistance to motion of 20N. To find the power being developed, one must calculate the potential energy gained over a distance of 20m and the time it takes to travel that distance. This will allow for the use of one of the power formulas (P = F*V or P = W/t).

## Homework Statement

a man of mass 70kg rides a bicycle of mass 15kg at a steady speed of 4 ms-1 up a road which rises 1.0 m for every 20m of its length. what power is the cyclist developing if there is a constant resistance to motion of 20N

## Homework Equations

(P= F*V) , ( p= W/t)

## The Attempt at a Solution

I suggest you work with a distance of 20 m. Figure out the height and potential energy gained over that distance. Figure out the time it takes to go 20 m. Then you will be in a position to use one of your power formulas.

## 1. What is the total mass of the man and the bicycle?

The total mass of the man and the bicycle is 85kg.

## 2. How does the mass of the man and the bicycle affect the speed?

The mass of the man and the bicycle does not directly affect the speed, as long as the force applied to the pedals is sufficient to overcome the resistance of the combined mass. However, a heavier mass may require more force to maintain a steady speed.

## 3. How is the speed of the bicycle calculated?

The speed of the bicycle can be calculated by dividing the distance traveled by the time taken to travel that distance. In this case, the speed is 4 meters per second.

## 4. What is the role of friction in this scenario?

Friction plays a crucial role in this scenario as it provides the resistance needed to maintain a steady speed. Without friction, the bicycle would continue to accelerate until an external force, such as air resistance, balances it out.

## 5. Is this scenario an example of Newton's First Law of Motion?

Yes, this scenario is an example of Newton's First Law of Motion, also known as the Law of Inertia. The man and the bicycle will continue moving at a constant speed in a straight line unless acted upon by an external force.