Post on 18-Dec-2015
A Projectile from a Cliff
Practice Quiz 3 # 10• A cannon is at the top of a cliff, 150 meters
high. The cannon fires a shell at an angle of 20° above the horizontal. The speed of the shell is 300 m/s as it leaves the muzzle of the cannon. How far from the base of the cliff does the shell land?
• v1 = 300 m/s
• v1x = 300 cos 20° = 282 m/s
• v1y = 300 sin 20° = 103 m/s
Time to Top of Trajectory
• Horiz Vert• v1 282 103• a 0 −10• v2 282 0
• t = (v2 − v1)/ a = 10.3
• 282 51.5 v̄�• s t=2890 t=676v̄�∙ v̄�∙
To the Top
• Doubling
Two Students
• Time from top to ground ?
• s = v1t + ½at2
• − 876 = 0 + ½ (−10) t2t2 = −876 / (−5) = 175.2
t = √175.2 = 13.3
The Whole Trip
• Horizontal Calculation• sx = t = 282 23.6 = 6653 metersv̄� ∙ ∙