PHYS 1006 Problem Set 3: Dynamics I
Using your textbook and lecture slides, provide complete answers to the following questions. Each question is out of 5 points, unless otherwise stated. The maximum grade for this problem set is 30 points. Show all conversions required and show all steps for full credit.
Note: Unless otherwise stated, assume no friction.
1. A 10 kg box rests on the table.
a. Determine its weight and the normal force acting on it.
b. If a 5 kg box is placed on top of the 10 kg box, determine the normal force that the 10 kg box exerts on the 5 kg box, and the normal force which the table exerts on the system.
2. [10 points] Can cars "stop on a dime"? To answer this question, calculate the acceleration caused if a car stops on a dime (diameter = 1.7 cm) from 30 km/h. How many g's is this? What is the force felt by the 70 kg occupant of the car? Given that people can only survive a force of 30 g's, will the person survive?
3. A person stands on a scale in a motionless elevator. When it begins to move, the scale reads 1.35 of their regular weight. Using this information, determine the magnitude and direction of the elevator's acceleration.
4. What is the difference between kinetic and static friction? Where would you see an example of both?
5. If the coefficient of kinetic friction between a 30 kg crate and the floor is 0.39, what horizontal force is required to move it at a steady speed across the floor? What force would be required if the coefficient of kinetic friction is equal to zero?
6. If a box is given a push such that its initial speed is 2.0 m/s, and the coefficient of kinetic friction is 0.25. How far will the box go?