A bike and cyclist have a combined mass of 75 kg. If the brakes can apply a maximum force of 20 N, what is the shortest time in which the cyclist can stop?

im confuse

To determine the shortest time in which the cyclist can stop, we can use Newton's second law of motion. The equation states that the net force acting on an object is equal to the mass of the object multiplied by its acceleration.

In this case, the net force acting on the bike and cyclist is the force applied by the brakes, which is 20 N. The mass of the bike and cyclist combined is given as 75 kg.

We need to find the acceleration of the bike and cyclist during deceleration, which is the same as the acceleration due to braking. Rearranging Newton's second law equation, we have:

Force = mass * acceleration

acceleration = Force / mass

acceleration = 20 N / 75 kg

acceleration ≈ 0.267 m/s^2

Now, to find the shortest time in which the cyclist can stop, we need to determine the time it takes for the cyclist to come to a complete stop. This can be done using the following equation of motion:

v = u + at

where:
v = final velocity (0 m/s as the cyclist comes to a stop)
u = initial velocity (unknown in this case)
a = acceleration (-0.267 m/s^2)
t = time taken

Rearranging the equation, we have:

t = (v - u) / a

As the cyclist comes to a stop, the final velocity v is 0 m/s. Therefore:

t = (0 - u) / (-0.267)

Simplifying:

t = u / 0.267

The shortest time in which the cyclist can stop would depend on their initial velocity (u). Without this information, we cannot determine the exact value for t.