Reports Due Friday • Review HW: Projectile Motion Problems 3

```Practice Problems for Projectile Motion
October 15, 2013
Today
• Finish Discussion of Lab; Reports Due Friday
• Review HW: Projectile Motion Problems 3
• 2nd Lunch
• Review Concepts in Projectile Motion
• Review Problems (handout in class)
Solution Guide - Honors Physics
1
Practice Problems for Projectile Motion
October 15, 2013
All Projectile Motion Problems:
v0x = v0Cosθ, v0y = v0Sinθ
ax = 0, ay = -9.8 m/s2
∆x = v0xt
∆y = v0yt + ½ayt2
vfy = v0y + ayt
vfy2 = v0y2 + 2ay∆y
Solution Guide - Honors Physics
2
Practice Problems for Projectile Motion
October 15, 2013
Type 1:
v0x = v0, v0y = 0
∆y, vfy are both NEGATIVE
Solution Guide - Honors Physics
3
Practice Problems for Projectile Motion
October 15, 2013
Type 2:
∆y = 0; this implies that vfy = -(v0y)
∆x = v02Sin(2θ)/9.8
Solution Guide - Honors Physics
4
Practice Problems for Projectile Motion
1.
October 15, 2013
A steel ball bearing is fired horizontally from a spring-loaded gun. The ball leaves the gun a height of 1.20 meters
above the floor, and lands on the ground after covering a horizontal displacement of 4.5 meters.
a) Determine the final vertical velocity of the ball bearing as it lands on the floor.
b) Determine the time required for the ball bearing to reach the floor.
c) Determine the initial velocity of the ball bearing in the horizontal direction.
Solution Guide - Honors Physics
5
Practice Problems for Projectile Motion
October 15, 2013
2. A soccer ball is rolled horizontally off of the top set of bleachers, and lands on the ground after falling for 0.70
seconds. Assume its initial horizontal velocity is 3.0 m/s.
a) What is the horizontal displacement of the soccer ball?
b) What is the height of the bleachers?
c) What is the final vertical velocity of the soccer ball just as it hits the ground?
Solution Guide - Honors Physics
6
Practice Problems for Projectile Motion
October 15, 2013
3. A slingshot launches a water balloon from the ground at a velocity of 15 m/s at an angle of 53 degrees. The water
balloon later lands back on the ground.
a) Determine the final vertical velocity of the water balloon just as it lands on the ground.
b) What is the total time the water balloon spends in the air?
c) What is the horizontal displacement of the water balloon?
Solution Guide - Honors Physics
7
Practice Problems for Projectile Motion
October 15, 2013
4. A frog leaps off the ground with an initial velocity of 2.0 m/s at an angle of 24 degrees. What is the horizontal
displacement of its leap?
Solution Guide - Honors Physics
8
Practice Problems for Projectile Motion
October 15, 2013
5. *A punter punts a football into the air such that it achieves a horizontal displacement of 40 meters when it is
caught by a returner at the same height as it was kicked. Assume that the football was in the air for a time of
5.0 seconds.
a) What is the horizontal component of the initial velocity?
b) *What is the vertical component of the initial velocity? [Hint: if the ball spends 5.0 seconds in the air, then it
takes just 2.5 seconds to reach the highest point...]
c) What is the initial velocity vector, in terms of its magnitude and direction?
Solution Guide - Honors Physics
9
Practice Problems for Projectile Motion
October 15, 2013
6. Standing on the edge of a cliff, a child tosses a stone into the air with an initial velocity of 6 m/s at an angle of
30 degrees. The stone lands on the ground after a time of 1.80 seconds.
a) What is the final vertical velocity of the stone?
b) What is the height of the cliff?
c) What is the horizontal displacement of the stone when it lands on the ground?
Solution Guide - Honors Physics
10
Practice Problems for Projectile Motion
October 15, 2013
7. Standing in front of a wall that is 5.0 meters away from you (horizontally), you take a tennis ball and release it from
a height of 1.40 meters above the ground such that its initial velocity is 10 m/s at an angle of 42 degrees.
a) How long does it take the tennis ball to hit the wall?
b) What is the vertical velocity of the tennis ball at this time?
c) How high above the ground is the tennis ball when it hits the wall?
Solution Guide - Honors Physics
11
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