physics

A box of books weighing 300N is shoved the floor of an apartment by a force of 400N exerted downward at an angle of 35.2 degrees below the horizontal. If the coefficient of kinetic friction between box and floor is .570, how long does it take to move the box 4.00 m, starting from rest?

Work:
(.570)300N=m(9.8m/s^2)
m=14.4 kg
400N=(30.6kg)a
a=27.8m/s^2
4m=(1/2)(27.8m/s^2)(sin 35.2)t^2
t=.71 sec

However, the answer is 3.16s.

  1. 👍
  2. 👎
  3. 👁
  1. No. The shoving force has a horizontal component, and a vertical component. The vertical component adds to the weight to make a greater fricton force.

    vertical component=300*Sin35.2
    horizontal component= 300 Cos35.2

    Friction= mu(mg + vertical component)
    net horizontal force=ma
    300cos35.2-friction= ma
    solve for a.
    Then, put it in the distance equation.

    1. 👍
    2. 👎
    👤
    bobpursley
  2. how long does it take to move the box 4.00m starting from rest?

    1. 👍
    2. 👎
  3. bob ur wrong

    1. 👍
    2. 👎
  4. 1.13 seconds

    1. 👍
    2. 👎
  5. 300 cos 35.2 - Fk = ma
    fk = 300 cos 35.2 - ma
    Fn = mg + 400 sintheta = 300 + 400 sin 35.2

    Fk = Fn*uk

    uk = 0.57

    300 cos 35.2 - ma = 0.57 [ 300 + 400sin 35.2]
    -ma = (0.57)[300+400sin35.2]- [300 cos 35.2]

    a = all that on the right side/ (300N/0.9)

    a = 0.8 m/s2

    Sx = VoT+ 1/2 at^2

    4= 0+ 1/2 (0.8) t^2
    t2 = 10
    t = 3.16 s

    1. 👍
    2. 👎

Respond to this Question

First Name

Your Response

Similar Questions

  1. physics

    a girl is using a rope to pull a box that weighs 300N across a level surface with constant velocity. the rope makes an angle of 30 degree above the horizontal and the tension in the rope is 100N. What is the normal force of the

  2. Physics

    A 25 kg box is along a horizontal floor and a force of 400 N pushes the box with an angle of 50 deg with the horizontal. Starting from rest, the box achieves a velocity of 2 m/s in a time of 4 seconds. Find the coefficient of

  3. physics

    A box of books weighing 319 N is shoved across the floor by a force of 485 N exerted downward at an angle of 35 degrees below the horizontal. a. If 'uk' between the box and the floor is 0.57, how long does it take to move the box

  4. physics

    A student pulls on a rope attached to a box of books and moves the box down the hall. The student pulls with a force of 182N at an angle of 25° above the horizontal. The box has a mass of 35kg and &mu k between the box and the

  1. Physics

    A student pulls a box of books on a smooth horizontal floor, ignore friction with a force of 131 N in a direction of 37° above the horizontal. If the mass of the box and the books is 33.7 kg, what is the acceleration of the box?

  2. Science-Enr. Phys.

    A box of books weighing 325 N moves at a constant velocity across the floor when the box is pushed with a force of 425 N exerted downward at an angle of 35.2 degrees below the horizontal. Fink Mu,k between the box and the floor.

  3. physics

    a delivery person pulls a 20.8 kg box across the floor. the force exerted on the box is 95.6n (35 above the horizontal). the force of kinetic friction on the box has a magnitude of 75.5n. the box starts from rest. using the

  4. Physics

    When a 300N force is applied to a box weighing 600N the box moves 3.0 horizontal in 20seconds

  1. physics

    A 50-kg box is being pushed a distance of 6.4 m across the floor by a force P with arrow whose magnitude is 154 N. The force P with arrow is parallel to the displacement of the box. The coefficient of kinetic friction is 0.24.

  2. Physics

    A 250N force is applied at an angle of 32 degrees above the horizontal to a 96kg box causing it to slide along a floor. The coefficient of friction between the box and the floor is 0.18. What is the magnitude of the net force on

  3. physics

    A box having a mass of 50kg is dragged across a horizontal floor by means of a rope tied on the front of it. The coefficient of friction between the box and the floor is .3. If the angle between the rope and the floor is 30

  4. Physics

    A box weighing 450 Newtons is pulled along a level floor at an angle of 30 degrees with the floor.If the force of the rope is 260 Newtons.What is the coefficient of sliding friction for the surface?

You can view more similar questions or ask a new question.