Physics Help? 1

Question

Blocks A (m_A = 5.00 kg) and B (m_B = 8.00 kg) are connected by a string that runs over an ideal, massless and frictionless pulley. The coefficient of friction between block A and the inclined plane is μ_k = 0.250. The system starts from rest. Use energy methods to determine the kinetic energy of block A after it moves a distance of 1.50 m along the inclined plane.(The angle block a is at is 30 degrees)

a.   What is the change in the potential energy of block A?         

      What is the change in the potential energy of block B?

 

b.   What is the work done by friction?               

c.   What is the common speed of the blocks?      

d.         What is the kinetic energy of block A?

Answer 1

(a)

Step 1:

Mass of the block A is 5 kg.

Mass of the block B is 8 kg.

The coefficient of friction between block A and the inclined plane is μ_k = 0.250.

Inclination angle is 30°.

Block A moves a distance of 1.50 m along the inclined plane.

Find the change in the potential energy of block A.

The change in potential energy can be given as .

The change in potential energy of block A is .

The change in potential energy of block A is 73.5 J.

The change in potential energy of block B is .

The change in potential energy of block B is 117.6 J.

Solution :

The change in potential energy of block A is 73.5 J.

The change in potential energy of block B is 117.6 J.

Answer 2

(b)

Step 1:

Mass of the block A is 5 kg.

Mass of the block B is 8 kg.

The coefficient of friction between block A and the inclined plane is μ_k = 0.250.

Inclination angle is 30°.

Work done by the friction is given as .

Where m is the mass of the block.

           g  is acceleration due to gravity (9.8 m/s²),

           μ_k  is coefficient of friction,

           is inclination angle.

Therefore work done by the frictional force is 10.60 J.

Solution :

Work done by the frictional force is 10.60 J.