Why do we have to keep pedaling (giving forces) the bike?...law of inertia...?

Question

The law of inertia states that no forces is required to maintain motion. Why do we have to keep pedaling the bicycle to maintain motion?

Answer 1

Frictional forces are working against us. These include air resistance, the friction of the working parts of the bike, the tyres on the road etc. If you are in empty space and are moving along at a steady speed there are no frictional forces and so you would keep moving at a steady speed.

Answer 2

There are two types of motion described in the relative motion of mass structures.
a)The motion due to Gravity power which is called non inertial.

b)The motion of any type of mass INcluding the micromasses of light, in the abscence of a Gravitational field, is called Inertial motion.

However; in both cases it is Power applied to a body ,that causes it to move. When a discrete amount Power is applied for a certain quantity of Time ,it will move with that particular discrete Energy & Velocity, and no more and no less

In the case of a bicycle as Power is applied to the pedal at zero plus seconds of Time ,the acceleration is maximum.Therefore; Force is maximum at the begining of the motion ,and as the bicycle picks up speed and motional energy ,as travel Time increases,the Force that you feel on the pedal becomes less and less.At a point where the Force is quasi zero the Velocity of the bicyle has reached its maximum.
So in order to make the bicyle go faster you must add additional Power and the bicyle will move at additional Velocity.

So the general rule of motion is the faster you move the more Power needs be added to the system .
The greater the speed of the motion the greater the Energy of motion.
You cannot make the bicyle go faster with the same Power input.This is the 2nd Law of Thermodynamics.

The bicycle would move with the same Power for ever ,according to Newton's law of Inertia.
However; because of friction ,air, tires etc..,more power needs to be added to make up for energy losses to maintain the same speed and energy of motion.
This is the Law of Entropy. It means that you cannot obtain the same work continuously without paying a Price and that is Energy loss to the surroundings (Its Entropy.)

In General its not the Force that causes motion relative to an inertial frame of reference. It is in reality Power that causes the inertial motion of mass structures.

In the Case of non inertial motion; it is Gravitational Power that causes bodies to move within the field of Space in the Universe.

Answer 3

Because there are negative forces acting on you while on a bike. Anything in motion in Earth's atmosphere experiences friction from the air around us. Also, the wheels, in contact with the ground, also provides friction. Therefore, you need to keep pedalling to counteract these forces. In deep space, where there is no friction, the satellites do not need to keep the rockets on to keep its speed.

Answer 4

One word: friction.

Friction is a force that tends to slow down and stop things. If you want to keep moving, you need to add energy to overcome friction.

Answer 5

Because there are many sources of friction converting your inertial velocity into useless heat and noise.

But of course there are exceptions. In space you can coast forever.