m2

m1

aT

PROBLEM 1

A cord passing over a frictionless pulley has a 4kg mass tied on one end and a 12kg mass on the other end. Compute the acceleration and tension of the cord.

Given: m1 = 12kg a = ?

m2 = 4 kg T = ?

Solution:

PROBLEM 2

An inclined plane makes an angle of 30° with the horizontal. Find the constant force applied parallel to the plane required to cause a 30kg box to slide (a) up the plane with acceleration

; (b) down the plane with acceleration

. Neglect friction.

Given: θ = 30° a =

m = 30kg F = ?

Solution:

Wx

30kg

30°

a

F

W

a.)

30°

30kg

a

F

W Wx

b.)

PROBLEM 3

It was found that a force of 360 N parallel to plane was required to move with constant velocity a 50kg mass up an inclined plane of 30°. Find the coefficient of sliding friction.

Given: F = 360 N θ = 30°

m = 50kg µ = ?

Solution:

Eq.1

Eq. 2

Wx

50kg

30°

F

W

f

Wy

PROBLEM 4

A metal block is placed on a horizontal oak board. The board is gradually tilted upward and the block just starts to slide when the inclination is 27°. Determine the coefficient of static friction between the block and the board.

Given: θ = 27°

µ = ?

Solution:

Eq. 1

Eq. 2

27°