Be sure tо shоw yоur work cleаrly аnd the equаtions you are using to solve each problem. You may not use derived equations if you do not show the derivation. All final answers should have the proper number of significant figures and include appropriate units. For any force diagrams be sure to show them quantitatively, if forces are different sizes that should be illustrated in your diagram. All problems are worth 12 pts. 21) A 42.0 kg child starts at rest and slides down a 15.0 m long water slide that is 9.0 m high. The coefficient of kinetic friction is 0.20 and there are no other drag forces present. (12 points) a) Draw a pictorial diagram with values and free body diagram. Be sure to show all forces and components as well. b) What is the child's acceleration? c) How much work is done by gravity? 22) Two brothers, Joe and Sam are riding scooters toward each other. Joe, the scooter and a backpack have a total mass of 56.5 kg and are moving to the left with a speed of 2.10 m/s. Sam and his scooter have a mass of 45.0 kg and are moving to the right with a speed of 1.50 m/s. As the brothers pass each other, Joe throws the 5.0 kg backpack to Sam to the left with a velocity of 1.00 m/s. (12 points) a) Draw a pictorial diagram with values labeled for the scenario. b) Neglecting any friction effects, what is Joe's new velocity after he throws the backpack to Sam? c) Neglecting any friction effects, what is Sam's new velocity after he catches the backpack? 23) A wagon is pulled to the left along a horizontal sidewalk. A force of 125 N is applied to the handle of a wagon that makes an angle of 30.0° from the horizontal. The brakes on the wagon are locked so that its wheels slide rather than roll. The wagon has a mass of 50.0 kg, and an acceleration to the right of 1.10 m/s/s. a) Draw a free body diagram for the wagon including all component forces. Label all forces. b) What is the coefficient of kinetic friction between the sliding wheels and the ground? 24) A Nerf gun with a 13.0 cm barrel is used to horizontally launch a 8.5 g plastic ball. The spring is compressed 9.0 cm as the ball is pushed into the barrel. When the trigger is pulled, the spring is released and the ball leaves the barrel with a velocity of 3.15 m/s. Assume that a constant frictional force of 0.052 N acts on the ball as it moves through the barrel. (12 points) a) Draw a pictorial diagram with values labeled. b) What is the spring constant of the Nerf gun? 25) A 75.0 kg person rides in a car that goes down a hill at a speed of 35.0 m/s. The shape of the hill is approximately circular, with a radius of 50.0 m, as in the figure. When the car is at the lowest point of the hill, a) Draw a force diagram for the person and name of the actual force that cause the person to move in a circle? b) What is the car's angular velocity in rads/s and rev/min? c) Find the normal force that acts on the person as they move through the bottom of the curve? d) What is the person's apparent weight at the bottom of the curve? Explain why their apparent weight is different than their actual weight.
A fаrmer in sоuthern Minnesоtа decides tо stop growing corn on one of her fields. She hаrvests the remaining corn, plows the field, and then does not alter the field any further. She notices that native prairie plants like big bluestem and silky asters begin to grow. This is an example of...