Think Like a Physicist 2

Why must a sharp shooter or an archer aim somewhat above her target? Why can't she simply aim directly at the bull's eye to hit it?

Think Like a Physicist

Out in deep space, far from any celestial object that exerts significant gravity, would an astronaut weigh anything? Would that astronaut have a mass?  Explain.

Projectile Motion Sample Problems 4 to 7

Please pardon my projectile hair. 

4.  A book slides off a horizontal table top with a speed of 4 mps.  It is observed to strike the floor in 0.5 seconds.  Find

a.      the height of the table top above the floor.

b.      the horizontal distance from the edge of the table to the point where the book strikes the floor.

c.       the horizontal and vertical components of its velocity when it reaches the floor. 

Please click on the link to see a bigger view: 

http://www.youtube.com/watch?v=4h0V-4TonDc 

5. A marksman fires a .22-caliber rifle horizontally at a target; the bullet has a muzzle velocity of 900 fps.  How much does the bullet drop in flight if the target is
       a.      50 yards away?
       b.      150 yards away?

Please click on the link to see a bigger view:

http://www.youtube.com/watch?v=nYZzUpO9LB0

6.  A baseball is thrown at an angle of 53^o above the horizontal with an initial speed of 40 mps.

a.      What is the maximum height above the thrower’s hand reached by the baseball?

b.      How long does it take to reach the maximum height?

c.       At what two times is the baseball at a height of 25 m above the point from which it was thrown?

Please click on the link to see a bigger view:

http://www.youtube.com/watch?v=kV5eonkVM6E

7.  A man stands on the roof of a building that is 50 m tall and throws a rock with a velocity of 60 mps at an angle 37^o above the horizontal.  Calculate:
a.      the maximum height, above the roof, reached by the rock;
b.      the magnitude of the resultant velocity of the rock just before it strikes the ground;
c.       the horizontal distance from the base of the building to the point where the rock strikes the ground.

Please click on the link to see a bigger view:

http://www.youtube.com/watch?v=mCp6WMy2Bd8

Projectile Motion Sample Problems

A projectile is an object upon which the only force acting is gravity. - physicsclassroom.com

1.  A baseball rolls on top of a flat roof 25 m high at a speed of 25 m/s.
a. The ball reaches the edge of the roof.  How long would it take the ball to reach the ground?
b. Find the range of the baseball.

Click on the link to see a bigger view: http://www.youtube.com/watch?v=VMcqnZbATAw

2. A basketball was thrown at a speed of 35 m/s and projected at an angle of 35⁰.
a.  How long will the basketball be in the air.
b.    Find the range of the basketball.

Click on the link to see a bigger view: http://www.youtube.com/watch?v=WdmbDiBudAc

3.  A motorcycle stunt rider rides off the edge of a cliff with a horizontal velocity of magnitude 5 mps.  Find the rider’s position and velocity after ¼ seconds.

Click on the link to see a bigger view: http://www.youtube.com/watch?v=C1UoytrdB7Q