Descending from rest at the last peak (height 20 m above the ground level) on a roller-coaster track, a car, of mass 750 kg, hits at the end of a horizontal stretch of shallow water, which exerts the average braking force of 920 N. How far does the car splash through the water before it stops? a. 210 m b. 160 m c. 130 m d. 90 m e. 50 m

You find yourself stranded on the middle of a frozen pond. The surface is so slick you are unable to get any traction. In an effort to save yourself, you take off your boot and throw it toward the west. This results in...    A. you staying put.            B. you sliding off to the east slower than the boot's speed.            C. you sliding off to the east faster than the boot's speed.            D. you sliding off to the west faster than the boot's speed.            E. you sliding off to the west slower than the boot's speed.

A high jumper with a body weight of 900N exerts an average vertical force of 2150N down on the floor for 0.50 s. The average vertical force exerted on the jumper by the floor is: a. 2150N b.1640N c. 900N d.3050N

C. a. 1. Alan (m = 50 kg) and Diego (m = 40 kg) are standing on a frictionless ice rink, facing each other, when Alan pushes Diego. Diego moves with an acceleration of 1 m/s². What is the magnitude of Alan's acceleration? a. .8 m/s² b. 1.0 m/s² c. 1.25 m/s² d. Cannot be determined 2. How much horizontal force must a girl apply to a 50 kg cabinet to accelerate it at .4 m/s² along a horizontal surface if there is a friction force of 70 N? b. 50 N e. 90 N 3. Students design an experiment to determine the relationship between mass and acceleration where a cannon fires varying masses. Motion sensors are used to measure the velocity of the cannon ball while it is in the cannon. A graph of one of the trials is shown to the right. The mass is then increased for the next trial while keeping everything else the same. What should the velocity vs. time graph look like for this next trial? The second trial is the dashed line. 120 100 80 60 40 20 0 0 120 100 80 60 40 20 a. 20 N d. 80 N D Velocity…

A 72 kg swimmer dives horizontally off a raft floating in a lake. The diver's speed immediately after leaving the raft is 3.8 m/s. If the time interval of the interaction between the diver and the raft is 0.25 s, what is the magnitude of the average horizontal force by diver on the raft? A. 270 N B. 68 N C. 2300 N D. 1100 N D B O A

16. Running without friction is impossible. In fact, to maximize your acceleration, you need to maximize the static friction between your shoes and the floor. a) Explain why static friction is necessary for running or walking. requirement, employees' shoes must have a coefficient of static friction of 0.5 or more on a specified tile surface. In an emergency, what is the minimum time interval in which a postal worker starting from rest can move a distance of 3 m on the tile surface? c) A typical athletic shoe has a coefficient of static friction of 0.8 when used on a running track. What is the minimum time interval in which an athlete starting from rest can move a distance of 100 m on a running track? b) To meet a U.S. Postal Service

q20

The question refers to a coin which is tossed straight up into the air. After it is released, it moves upward, reaches its highest point and falls back down again. Use one of the following choices (A through G) to indicate the force acting on the coin in the case described below. Answer choice J if you think that none is correct. Ignore any effects of air resistance. The coin is moving downward. A. The force is down and constant. B. The force is down and increasing C. The force is down and decreasing D. The force is zero. E. The force is up and constant. F. The force is up and increasing G. The force is up and decreasing O A O ΟΕ D OF O o J

⦁ Explain why you would rather fall 10 ft onto a featherbed than on concrete using physics

4.5 A load of lumber of weight W = 25 kN is being raised by a mobile crane. The weight of boom ABC and the combined weight of the truck and driver are as shown. Determine the reaction at each of the two (a) front wheels H, (b) rear wheels K.