Monday, January 18, 2016

EJSS Free Fall simulation added more scenarios

http://iwant2study.org/ospsg/index.php/interactive-resources/physics/02-newtonian-mechanics/01-kinematics/37-kinematics-in-y-direction
From Dave and Gavin,

1. A sky diver jumps out of a hovering helicopter. A 2 seconds afterwards another sky diver jumps out and they both fall along the same vertical line. Ignore air resistance so that both sky divers fall with the same acceleration.
a. Does the difference in their speeds stay the same throughout the fall?

 http://iwant2study.org/ospsg/index.php/interactive-resources/physics/02-newtonian-mechanics/01-kinematics/37-kinematics-in-y-direction
suggested answer: after t =2 s, the difference is always the same difference as shown by the constant difference.

b. Does the vertical distance between them stay the same throughout the fall?

 http://iwant2study.org/ospsg/index.php/interactive-resources/physics/02-newtonian-mechanics/01-kinematics/37-kinematics-in-y-direction

suggested answer: after t =2 s, the difference in position increases as shown by the increasing difference of YELLOW minus BLUE line.

Question 2

2. A tennis ball thrown from the top of a building is given an initial velocity of 20 m/s straight upward. The building is 50 m high, and the ball just misses the edge of the roof on its way down. Using t = 0 as the time the ball leaves the thrower’s hand, determine
a. the time at which the ball reaches its maximum height

 http://iwant2study.org/ospsg/index.php/interactive-resources/physics/02-newtonian-mechanics/01-kinematics/37-kinematics-in-y-direction
suggested answer: t = 2.0 s

b. the maximum height

suggested answer: H maximum = 70.4 m

c. the time at which the ball returns to the height from which it was thrown

 http://iwant2study.org/ospsg/index.php/interactive-resources/physics/02-newtonian-mechanics/01-kinematics/37-kinematics-in-y-direction

suggested answer: t = 4.0 or 4.1 s

d. the velocity of the ball at this instant

suggested answer: v = -20.2 m/s

e. the velocity and position of the ball at t = 5 s

 http://iwant2study.org/ospsg/index.php/interactive-resources/physics/02-newtonian-mechanics/01-kinematics/37-kinematics-in-y-direction
suggested answer: y = 27.4 m and v = -29.1 m/s