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1) A skateboard track has the form of a circular are with a 4.00 m radius, extending to an angle of 90 degrees relative to the vertical on either side of the lowest point. A 57.0 kg skateboarder starts from rest at the top of the circular arc. What is the normal force exerted on the skateboarder at the bottom of the circular arc?

2) A 135-g rubber ball is thrown with a speed of 12m/s at an oncoming 1100-kg car which is approaching at 35 m/s, and undergoes a one-dimensional elastic collision with the car.

a) What is the speed of the ball after the collision

b) Show that kinetic energy of the ball is conserved

Answers: a)Vf, ball=70.16 m/s b) KEi=KEf=1.35x10^6J

3) a plate falls vertically to the floor and breaks up into three pieces, which slide along the floor. Immediately after the impact, a 245-g piece moves along the x-axis with a speed of 2.50 m/s, a 275-g piece moves along the y-axis with a speed of 1.50m/s. The third piece has a mass of 100g. What are the magnitude and direction of its velocity?

Answer: V3=7.384 m/s and Theta = 34 degrees

I do not know how to solve these equations can someone please show me the work so I can learn the appropriate equations to use and how to use them so I can solve the rest of my questions on my own thanks!