Kinematics and Freefall - Solved Problems скачать в хорошем качестве

Kinematics and Freefall - Solved Problems

In this video we go over kinematics and freefall example problems. Each practice problem should be attempted before following the solution provided to really benefit from these examples. 0:15 - You run from point X to point Y to point Z in 4.0 s. What is your average velocity over this period of time? 0:45 - A football quarterback runs 15.0 m straight down the playing field in 2.50 s. He is hit and pushed 3.00 m straight backward in 1.75 s. He breaks a tackle and runs straight forward another 21.0 m in 5.20 s. Calculate his average velocity (a) for each interval and (b) for the entire motion. 2:10 - A cheetah can accelerate from rest to a speed of 30 m/s in 7.00 s. What is its acceleration assuming it is constant? 3:26 - A commuter backs her car out of her garage with an acceleration of 1.40 m/s^2. (a) How long does it take her to reach a speed of 2.00 m/s? (b) If she then breaks to a stop in 0.800 s, what is her deceleration? 5:20 - In a slap shot, a hockey player accelerates the puck from a velocity of 8.00 m/s to 40.0 m/s in the same direction. If the shot takes 3.33 x 10^-2 s, calculate the distance over which the puck accelerates. 6:20 - Calculate the displacement and velocity at times of (a) 0.500 s, (b) 1.00 s, (c) 1.50 s, and (d) 2.00 s for a ball thrown straight up with an initial velocity of 15.0 m/s. Take the point of release to be y_0 = 0. 7:41 - A basketball referee tosses the ball straight up for the starting tip-off. At what velocity must a basketball player leave the ground to rise 1.25 m above the floor in an attempt to get the ball? 8:47 - (a) Calculate the height of a cliff if it takes 2.35 s for a rock to hit the ground when it is thrown straight up form the cliff with an initial velocity of 8.0 m/s. (b) How long would it take to reach the ground if it is thrown down with the same speed? 11:28 - A kangaroo can jump over an object 2.50 m high. (a) Calculate its vertical speed when it leaves the ground. (b) How long is it in the air? 13:44 - A coin is dropped from a hot-air balloon that is 300 m above the ground and rising at 10.0 m/s upward. For the coin, find (a) the maximum height reached, (b) its position and velocity 4.00 s after being released, and (c) the time before it hits the ground. 17:05 - A bus is traveling down the interstate at 30 m/s. A car moving at a constant 50 m/s passes the bus. The moment the car the bus, the bus begins accelerating at a constant rate of 2.5 m/s^2 to catch the car. (a) How long will it take the bus to catch the car? (b) How far down the road will the bus travel before catching the car? 18:55 - Excited to test your knowledge of physics, you go to the roof of the tallest building on campus, 46.0 m above the ground. Your least favorite instructor who is 1.8 m tall, walks along the side of the building at a steady 1.2 m/s. You want to drop an egg and hit your instructor in the head. How far away should the instructor be when the egg is released? 20:36 - The position of a particle is given by a function x(t) = (2t^3 - 6t^2 + 12) m, where t is in seconds. (a) At what time does the particle reach its minimum velocity? What is v_min? (b) At what time is the acceleration zero?