physical aspects of nature

posted by .

A 1,440-N crate is being pushed across a level floor at a constant speed by a force of 250 N at an angle of 20.0° below the horizontal;
(a) What is the coefficient of kinetic friction between the crate and the floor?
(b) If the 250-N force is instead pulling the block at an angle of 20.0° above the horizontal, as shown in the figure (b), what will be the acceleration of the crate? Assume that the coefficient of friction is the same as that found in part (a).

  • physical aspects of nature -

    Fc = 1440N @ 0 Deg. = Force of crate.
    Fp = 1440*sin(0) = 0 = Force parallel to floor.
    Fv = 1440*cos(0) = 1440 N. = Force perpendicular to floor.

    Fv' = Fv + Fap*sin20.
    Fv'=1440 + 250*sin20 = 1526 N=Normal.

    a. Fn = Fap - Fp - u*Fv' = 0.
    250*cos20 - 0 - u*1526 = 0.
    1526u = 250*cos20 = 235.
    u = 235 / 1526 = 0.154 = Coefficient of kinetic friction.

    b. mg = 1440 N.
    m = 1440/g = 1440 / 9.8 = 147 kg = Mass
    of crate.

    Fv' = 1440 - 250*sin20 = 1354 N. =[Normal.

    Fn = Fap - Fp - u*Fv' = ma.
    250*cos20 - 0 - 0.154*1354 = 147a.
    235 - 209 = 147a.
    147a = 26.
    a = 26 / 147 = 0.177 m/s^2.

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. ap physics

    A 1.20*10^2 kg crate is being pushed across a horizontal floor by a force P that makes an angle of 30.0° below the horizontal. The coefficient of kinetic friction is 0.350. What should be the magnitude of P, so that the net work done …
  2. physics

    A 1.20*10^2 kg crate is being pushed across a horizontal floor by a force P that makes an angle of 30.0° below the horizontal. The coefficient of kinetic friction is 0.350. What should be the magnitude of P, so that the net work done …
  3. physics

    A 1100 N crate is being pushed across a level floor at a constant speed by a force of 500 N at an angle of 20.0° below the horizontal. (a) What is the coefficient of kinetic friction between the crate and the floor?
  4. Physics

    A 1200-N crate is being pushed across a level floor at a constant speed by a force of 260 N at an angle of 20.0° below the horizontal. (a) What is the coefficient of kinetic friction between the crate and the floor?
  5. physics

    A 1,440-N crate is being pushed across a level floor at a constant speed by a force of 210 N at an angle of 20.0° below the horizontal, as shown in the figure (a) below (a) What is the coefficient of kinetic friction between the crate …
  6. physics

    A 1,040-N crate is being pushed across a level floor at a constant speed by a force of 350 N at an angle of 20.0° below the horizontal; (a) What is the coefficient of kinetic friction between the crate and the floor?
  7. physics

    A 1,080-N crate is being pushed across a level floor at a constant speed by a force of 290 N at an angle of 20.0° below the horizontal, as shown in the figure (a) below. (a) What is the coefficient of kinetic friction between the …
  8. physics

    A 1,440-N crate is being pushed across a level floor at a constant speed by a force vector F of 380 N at an angle of 20.0° below the horizontal, as shown in the figure (a) below. (a) What is the coefficient of kinetic friction between …
  9. Physics

    A 1000N crate is being pushed across a level floor at a constant speed by a force F of 300N at an angle of 20.0 degrees. (a) What is the coefficient of kinetic friction between the crate and the floor?
  10. Physics

    A 1000N crate is being pushed across a level floor at a constant speed by a force F of 300N at an angle of 20.0 degrees. (a) What is the coefficient of kinetic friction between the crate and the floor?

More Similar Questions