Unit B Assessment

 

A roofer is dragging a 15.0-kg bundle of shingles up the roof using a light rope parallel to the roof. The roof is sloped at an angle of 30.0° with the horizontal.

  1. Draw a free-body diagram of the forces involved.

  2. What is the force component perpendicular to the roof of the weight of the bundle of shingles?

  3. What is the magnitude of the force of friction on the bundle of shingles as it is pulled up the roof? The coefficient of kinetic friction of the shingle bundle on the roof is 0.520.

  4. Calculate the force parallel to the roof with which the roofer must pull on the rope to move the shingles at constant speed up the roof.

  5. Suppose an astronaut was building a similar structure on Mars. What would be the force component perpendicular to the roof of the weight of a 15.0-kg bundle of materials on the surface of Mars? The mass of Mars is 6.42 × 1023 kg, and the radius of Mars is 3.40 × 106 m.



  6. Between Mars and Jupiter, the asteroid Ceres orbits the Sun at an average radius of 2.766 AU. Use Kepler’s third law to calculate the time in Earth years it takes for Ceres to make one complete orbit.

Submit your answers to the Unit B Assessment to your teacher for marks.