Calculate the acceleration of the cyclist

In summary, a Grade 11 physics student is struggling with a question about a cyclist coming to a stop. The student is attempting to use a formula but is not getting the correct answer. The solution involves calculating the acceleration of the cyclist and determining the coefficient of friction between the road and the bike. The mass of the cyclist and bike is given as 73kg but is ultimately found to not affect the calculation.
  • #1
bonfire89
Question...
Hi, I'm a Grade 11 physics student who is having a difficult time on this one question.. Any help would be greatly apretiated.


A cyclist is traveling at 21km/h when she sees a stop sign ahead. She applies the brakes and comes to a stop in 15m. The mass of the cyclist and the bike is 73kg.

a)Calculate the acceleration of the cyclist.
b) Determine the coeficient of friction between the road and the bike.


currently for question a I am atempting to use
v1^2 - v2^2 = 2 * d * a
but I am not getting the right answer


Thanks!
 
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  • #2
21 km/h =~ 5.838 m/s

a = (0 - 5.838)/900 = -0.0064866666666666666666666666666667m/s^2

ΣF = -μkFN = ma

-μkmg = ma

-μkg = a

μk = -(a/g) = 6.6190476190476190476190476183673e-4


as you can see, mass don't matter.
 
  • #3
awsome! thank you. I am currently doing other porblems, but I shall come back to then, and learn what you did..

THank you!
 

1. What is acceleration?

Acceleration is the rate at which an object's velocity changes over time. It is a measure of how quickly an object is speeding up or slowing down.

2. How do you calculate acceleration?

Acceleration can be calculated by dividing the change in an object's velocity by the time it takes for that change to occur. The formula for acceleration is: a = (vf - vi) / t, where a is acceleration, vf is final velocity, vi is initial velocity, and t is time.

3. How is acceleration related to force?

According to Newton's second law of motion, acceleration is directly proportional to the net force acting on an object, and inversely proportional to the object's mass. This means that the greater the force applied to an object, the greater its acceleration will be.

4. Can acceleration be negative?

Yes, acceleration can be negative. A negative acceleration, also known as deceleration, means that an object is slowing down. This can happen when there is a negative net force acting on the object, such as friction or air resistance.

5. How does a cyclist's acceleration affect their speed?

A cyclist's acceleration directly affects their speed. If the cyclist is accelerating, their speed will increase. If the cyclist is decelerating, their speed will decrease. The magnitude of the acceleration will determine how quickly the speed changes.

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