A) The forward force is equal to the backward force
In this problem:
- the forward force is the force that Megan applies to the pedal to go forward
- the backward force is due to the air resistance and the friction between the wheels and the track
In this case, Megan is travelling at constant speed. This means that her acceleration is zero:
a = 0
According to Newton's second law, the resultant of the forces acting on Megan is equal to the product between mass (m) and acceleration (a):
However, a = 0, so the resultant of the forces is also zero:
and this implies that the forward force and the backward force are equal in magnitude and opposite in direction.
B) The forward force is larger than the backward force
In this case, Megan crouched down in order to make herself more streamlined. As a result, the air resistance acting on Megan will decrease: so, the backward force will decrease, and therefore the forward force (which has remained the same) will be larger than the backward force.
So, the resultant force
will be no longer zero, and therefore the acceleration will be different from zero, which means that Megan will increase her speed.
The sun warms the planet, drives the hydro logic cycle, and makes life on Earth possible. The amount of sunlight received on Earth's surface is affected by the reflectivity of the surface, the angle of the sun, the output of the sun, and the cyclic variations of Earth's orbit around the sun.