6. Intro to Forces (Dynamics)
Forces & Kinematics
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- Multiple Choice
An 800-kg car is traveling along a horizontal road directly towards a cliff. The driver notices and brakes, resulting in a 5,000-N net force slowing the car down. If the car's initial speed was 20 m/s and the car stops just before going over the cliff, how far away was the car from the cliff when the driver hit the brakes?
2945views68rank5comments - Multiple ChoiceThe following forces are acting on a box on a horizontal surface. A downward force of gravity with magnitude . An upward normal force with magnitude . A rightward pull from a rope of . A leftward kinetic friction force with magnitude . At this instant, what is the magnitude of the acceleration of the box?1314views1rank1comments
- Multiple ChoiceTabletop shuffleboard is a popular pub game where players slide pucks across a tabletop trying to get them as close to the end of the table as possible, without falling off. Shuffleboard tables are typically covered in shuffleboard wax, which gives a very low coefficient of kinetic friction between the table and puck. Suppose that one particular table is 6.0 long m and has a coefficient of kinetic friction of 0.080. What speed should a player give to a puck on one end of the table so the puck just makes it to the far end?1474views1comments
- Textbook Question
(II) A child on a sled reaches the bottom of a hill with a velocity of 10.0 m/s and travels 25.0 m along a horizontal straightaway to a stop. If the child and sled together have a mass of 60.0 kg, what is the average retarding force on the sled on the horizontal straightaway?
1421views - Textbook Question
When jumping straight up from a crouched position, an average person can reach a maximum height of about cm. During the jump, the person's body from the knees up typically rises a distance of around cm. To keep the calculations simple and yet get a reasonable result, assume that the entire body rises this much during the jump. With what initial speed does the person leave the ground to reach a height of cm?
1150views - Textbook Question
FIGURE EX6.10 shows the force acting on a 2.0 kg object as it moves along the x-axis. The object is at rest at the origin at t = 0 s. What are its acceleration and velocity at t = 6 s?
2432views2rank - Textbook Question
The forces in FIGURE EX6.9 act on a 2.0 kg object. What are the values of ax and ay, the x- and y-components of the object's acceleration?
3073views - Multiple ChoiceA 40-kg crate is being lowered with a downward acceleration of 2.0 m/s² by means of a rope. What is the magnitude of the force exerted by the rope on the crate?875views