Answer:
A). A Lever and Wheel and Axle.
Explanation:
1. A wheel axle is most obvious, as the wheels are connected via a chain and axle with spokes. This helps keep the wheels moving forward with less effort than walking.
2. A Lever is used to help Balance you as you ride the bike. Without it, you would tip over, and lose all the momentum you had gained up until that point.
3. (I took the test on e2020)
Unbalanced force.
The definition of an unbalanced force is a force that changes the position, speed or direction of the object to which it is applied.
When an object is still it means that is is balanced force. So you would need to add more force to another side to make it move. Which is unbalanced force.
Edit
In physics, power is the rate of doing work or of transferring heat, i.e. the amount of energy transferred or converted per unit time. Having no direction, it is a scalarquantity. In the International System of Units, the unit of power is the joule per second (J/s), known as the watt in honour of James Watt, the eighteenth-century developer of the condenser steam engine. Another common and traditional measure is horsepower (comparing to the power of a horse). Being the rate of work, the equation for power can be written:
Power
Common symbols
Derivations from
other quantities
P = E/t
P = F·v
P = V·I
P = T·ω
As a physical concept, power requires both a change in the physical system and a specified time in which the change occurs. This is distinct from the concept of work, which is only measured in terms of a net change in the state of the physical system. The same amount of work is done when carrying a load up a flight of stairs whether the person carrying it walks or runs, but more power is needed for running because the work is done in a shorter amount of time.
The energy associated with an object's motion is called kinetic energy. ... This is also called thermal energy – the greater the thermal energy, the greater the kinetic energy of atomic motion, and vice versa.
