October 1
A football punter accelerates a football from rest to a speed of 10 m/s during the time in which his toe is in contact with the ball (0.20 s). If the football has a mass of 0.50 kg, what average force does the punter exert on the ball?September 29
What is Force?September 26
Some practice problems:Chapter 2: 62, 63, 71
Chapter 3: 63, 65, 69
September 24
A projectile is fired with an initial speed of Vo at an angle theta to the horizontal. When it reaches its peak, the projectile has (x,y) coordinates given by (R/2, h) and when it strikes the ground, its coordinates are (R, 0), where R is the horizontal range and h is the maximum height.Show that the horizontal range of the projectile is given by R = (Vo^2 sin 2 theta)/g.
September 19
A ball is projected horizontally from the top of a building. One second later, another ball is projected horizontally from the same point with the same velocity.a) At what point in the motion will the balls be closest to each other?
b) Will the first ball always be traveling faster than the second?
c) What will be the time difference between them when the balls hit the ground? d) Can the horizontal projection velocity of the second ball be changed so that the balls arrive at the ground at the same time?
September 18
Eileen kicks a soccer ball to David at 17 m/s at an angle of 24 degrees from the ground.a) How long is the ball in the air?
b) How far away is David?
c) How high does the ball go?