A bicycle and its rider together have a mass of 80 kg. If the bicycle's speed is 6m/s, how much force is needed to bring it to a stop in 4 seconds.
5.6
To determine the force required to bring the bicycle to a stop, we need to use Newton's second law of motion, which states that force (F) is equal to the mass (m) multiplied by the acceleration (a). In this case, we need to find the acceleration.
Given the initial speed of the bicycle (u) as 6 m/s, the final speed (v) as 0 m/s (since we want to bring it to a stop), and the time taken (t) as 4 seconds, we can use the equation for acceleration:
a = (v - u) / t
Plugging in the values, we get:
a = (0 m/s - 6 m/s) / 4 s
= -6 m/s / 4 s
= -1.5 m/s^2
Note that the negative sign indicates that the bicycle is decelerating.
Now that we know the acceleration, we can calculate the force required using Newton's second law:
F = m * a
Given that the mass (m) of the bicycle and rider together is 80 kg, we can substitute the values:
F = 80 kg * -1.5 m/s^2
= -120 N
The negative sign indicates that the force is acting in the opposite direction of motion, which corresponds to the deceleration of the bicycle.
Therefore, the force required to bring the bicycle to a stop in 4 seconds is 120 Newtons, opposite to the direction of motion.