Hi, can you please help me solve the following problem? It\'s notfrom a textbook

Question

Hi, can you please help me solve the following problem? It's notfrom a textbook, but we use the Giancoli Textbook as a resource.I can't figure this problem out. Can you please helpme by providing a step by step process of how you approached theproblem. Please make sure the answer matches the ones providedbelow. Thank you!

(a) Your bike is upside-down, and you made the front wheelspin at 4.0 revolutions/s. Then you apply a steady force on thebrake, and the wheel stops in a quarter of a turn. Assuming theangular acceleration was constant, what was its value?
Ans.: -64 = -201 rad/s.

(b) What total torque were the brake pads causing? Thediameter of the wheel is 26” (1 inch = 2.54 cm) and its massis 3 lbs (1 kg = 2.2 lbs); use the approximation that the entiremass of the wheel is uniformly distributed along therim.
Ans.: 145 Nm

(c) If the coefficient of kinetic friction between thebrake pads and the wheel rim is k = 0.6, with what force was eachof the two brake pads pressing onto the rim?
Ans.: 365 N.

Explanation / Answer

Let's do it (a) Your bike is upside-down, and youmade the front wheel spin at 4.0 revolutions/s. Then you apply asteady force on the brake, and the wheel stops in a quarter of aturn. Assuming the angular acceleration was constant, what was itsvalue? = /t ; then t= / while =0.5t2 = 4.0 x 2 = 8.0 rad/s = 1/4(2) = /2 = 2/t2 =2/(/)2    = 0.5 2 /2 = 0.5 x (8.0 ) 2 //2 = -64 rad/s   (negative sinse the wheel isbreaking)
Ans.: -64 = -201rad/s. - (b) What total torque were the brakepads causing? The diameter of the wheel is 26” (1 inch = 2.54cm) and its mass is 3 lbs (1 kg = 2.2 lbs); use the approximationthat the entire mass of the wheel is uniformly distributed alongthe rim.

=I
For a wheel approximating a thin walled cylindrical shape
I= mr2   then
=(mr2)
=((3/2.2)((26/2) x2.54/100)2) (-64)
=

Ans.: 145Nm

(c) If the coefficient of kinetic frictionbetween the brake pads and the wheel rim is k = 0.6, with whatforce was each of the two brake pads pressing onto therim? Since by definition =rFsin() and in our case=90 degrees we hav e =rF and F= / r BRB
Ans.: 365 N.

Related Questions

Navigate

• Browse (All)
• Browse H
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.