Assignment #3 Problems
For Exam 2, you will be expected to do problems of difficulty similar to those below without reference to the text or to any notes. Make sure that you can do this before you move on to the next assignment!
Graded Homework Problems
Do Assignments 3A and 3B at www.masteringphysics.com .
Mandatory Homework Problems
(1) Can an object accelerate if its speed is constant? Can an object accelerate if its velocity is constant?
(2) State which of the following quantities, if any, remain constant as a projectile moves through its parabolic trajectory: (a) speed, (b) acceleration, (c) horizontal component of velocity, (d) vertical component of velocity.
(3) Twenty people participate in a tug-of-war. The two teams of ten people are so evenly matched that neither team wins. After the game, they notice that a car is stuck in the mud. They attach the tug-of-war rope to the bumper of the car, and all the people pull on the rope. The heavy car has just moved a couple of decimeters when the rope breaks. Why did the rope break in this situation when it did not break when the same twenty people pulled on it in a tug-of-war?
(4) The driver of a speeding empty truck slams on the brakes and skids to a stop through a distance d. (a) If the truck carried a load that doubled its mass, what would be the truck's “skidding distance”? (b) If the initial speed of the truck were halved, what would be the truck's skidding distance?
(5) A woman at an airport is towing her 20.0 kg suitcase at constant speed by pulling on a strap at an angle q above the horizontal. She pulls on the strap with a 35.0 N force, and the friction force on the suitcase is 20.0 N. Draw a free-body diagram of the suitcase. (a) What angle does the strap make with the horizontal? (b) What normal force does the ground exert on the suitcase?
(6) A 3.00 kg block starts from rest at the top of a 30 degree incline and slides a distance 2.00 meters down the incline in 1.50 seconds. Find (a) the magnitude of the acceleration of the block, (b) the coefficient of kinetic friction between block and plane, (c) the frictional force acting on the block, and (d) the speed of the block after it has slid 2.00 meters.