<p>Phys 221 SI WS 9: What equation do I use?</p><p>3. Tell which equation would be used to solve each problem. If multiple equations work, write down all that apply and underline the one(s) that would be easiest. 1) A 1000 kg car makes a 30 m radius turn at a speed of 60 mph. What force must the brakes apply?</p><p>2) You throw a ball straight up in the air with a speed of 20 m/s. What is its position after 1.5 seconds?</p><p>3) A ball makes it around a circle once every 10 seconds. What is the frequency of the motion?</p><p>4) The angular velocity is given by . What is the angular acceleration?</p><p>5) A child runs around in a 5 m circle at a speed of 2 m/s. How long does it take the child to make one circle? Also, how many circles does the child make every second, on average?</p><p>6) You shoot a projectile from a cannon and you want to know how high it goes.</p><p>7) You shoot a projectile from a cannon and you want to know how far it goes.</p><p>8) As a car passes another car in a quarter turn of radius 100 m, it must accelerate uniformly from 50 mph to 70 mph. What is its total acceleration? (Assume the car stays in the same lane for the duration of the turn, and assume no friction is present)</p><p>9) . What is the velocity and acceleration of the object?</p><p>10) An object in uniform circular motion (radius 2 m) undergoes constant angular acceleration for 3 seconds, and starts at an angular speed of 2 rad/s. What distance (measured in meters) did the object travel in those three seconds? What is its speed at that time?</p><p>11) A 30 g bullet is fired into a tree at a speed of 100 m/s. It gets stuck in the tree 1 meter through (it’s a big tree!). What is the frictional force applied by the tree? (Assume its constant)</p><p>12) A boy jumps onto a cart at the grocery store and they travel together 3 meters before the cart comes to a stop due to friction. Considering that the boy-cart have a combined mass of 50 kg, and that the boy was traveling 2 m/s when he and the cart first start moving, what is the coefficient of friction between the cart and the ground?</p><p>13) A block on a 30 degree incline remains motionless. What is the smallest coefficient of static friction possible?</p><p>14) A robber moving at 50 mph shoots a bullet backward with a speed of 200 mph relative to the gun. How fast is the bullet moving towards the stationary cops?</p>