STUDY GUIDE UNIT 7 - PROJECTILES

Transcription

1 Name Mods STUDY GUIDE UNIT 7 - PROJECTILES Date Agenda Homework Tues 11/17 Wed 11/18 Thurs 11/19 Fri 11/20 Mon 11/23 Tues 11/24 Lab - Projectiles Share Lab Data Go over lab Start problem set 1 Go over problem set 1 Begin problem set 2 Go over problem set 2 Begin problem set 3 Go over problem set 3 Quiz-horizontal projectiles Read section 3.4 in textbook and take notes in packet Watch video #1 and take notes in the packet Finish problem set 1 -Finish problem set 2 -Watch video #2 and take notes in packet Finish problem set 3 Wed 11/25 Work on problem set 4 Finish problem set 4 1

2 Equations Sheet 2

3 CP Physics Reading Notes Section List four examples of projectiles,,, 2. Roll a ball along a horizontal surface, and its velocity is because no component of gravitational force acts 3. Drop a ball, and it and covers a vertical distance every second 4. The horizontal component of motion for a projectile is of the vertical component of motion 5. Their produce the variety of curved paths that a projectile follows 3

4 VIDEO NOTES 1-PROJECTILES 4

5 CP Physics Horizontal Projectiles Problem Set #1 FOR EACH OF THE FOLLOWING, IGNORE THE EFFECTS OF AIR RESISTANCE SHOW ALL WORK! 1. A cannon is shot horizontally at a speed of 360 m/s off of a cliff 135 meters high. How far away from the bottom of the cliff will the cannonball strike the ground? a. Draw a diagram to summarize the information b. Calculate the time it takes to hit the ground c. Calculate how far from the bottom of the cliff 5

6 2. Billy the Bowler rolls a ball off the edge of his 75 meter tall building at a speed of 12.5 m/s. How far from the building will the ball hit the cat walking across the street below? a. Draw a diagram to summarize the information b. Calculate the time it takes for the ball to hit the ground c. Calculate how far from the building the cat was 6

7 3. A pool ball leaves a 0.60-meter high table with an initial horizontal velocity of 2.4 m/s. Predict the time required for the pool ball to fall to the ground and the horizontal distance between the table's edge and the ball's landing location. a. Draw a diagram to summarize the information b. Calculate the time it takes to hit the ground c. Calculate the horizontal distance from the table 7

8 CP Physics Horizontal Projectiles Problem Set #2 FOR EACH OF THE FOLLOWING, IGNORE THE EFFECTS OF AIR RESISTANCE SHOW ALL WORK! 1. A girl fires a rifle at a paper target on a rifle range. Assuming the rifle is pointed exactly horizontal (1.75 m above the ground) when the bullet is fired (at 500 m/s), how far from the girl will the bullet land? (assume that the paper target won't slow the bullet down) 2. A kid's marble rolls off a 63 cm tall table at a speed of 30 cm/s. How far from the base of the table will the ball land? 8

9 3. The pilot of a hot air balloon and his girlfriend are having a good time floating along 500 ft above the ground. The wind is pushing them sideways at 10 ft/s. If they accidentally knock a soda bottle overboard, how far forward of the place it was dropped will the bottle land (solve for dx)? 4. An American Indian fires an arrow perfectly horizontal (1.5 m above the ground) at a speed of 35 m/s. If it hits the ground, how far in front of her will the arrow land? 9

10 VIDEO NOTES #2 - HORIZONTAL PROJECTILES 10

11 CP Physics Horizontal Projectiles Problem Set #3 FOR EACH OF THE FOLLOWING, IGNORE THE EFFECTS OF AIR RESISTANCE SHOW ALL WORK! 1. A plane flying at 120 m/s drops a huge canister containing C.A.R.E. packages to a village below. If the plane needs to drop the canister 1200 m before it flies over the village (in order to hit the target) how high is the plane? 2. A careless mountain climber drops an unopened can of soup on some ice. The can rolls along on the ice at a constant speed of 5 m/s. Assuming the can left the top of a cliff, and landed 3.9 m away from the base of the cliff: a. How tall was the cliff? b. How adventurous is this mountain climber? 11

12 3. Jennifer tried to throw a piece of garbage into the trash can. She threw it perfectly horizontal at a speed of 4 m/s, but being an awful shot, Jen missed the trash can and hit the teacher's foot. Assuming the teacher was 2 m away from Jen, how much higher than the teacher's foot was Jen's hand when she let go of the garbage? 4. A ball rolls off a table at 1.45 m/s. Assuming it lands 80 cm from the base of the table, how tall is the table (in meters)? 12

13 CP Physics Horizontal Projectiles Problem Set #4 FOR EACH OF THE FOLLOWING, IGNORE THE EFFECTS OF AIR RESISTANCE SHOW ALL WORK! 1. A bullet with a perfectly flat trajectory comes out of a.50 cal Barrett rifle that Is positioned 0.3m above perfectly flat ground and lands m away. How fast was the bullet traveling when it left the rifle barrel? 2. A little kid is sliding her sled in the snow and goes over a little 87cm high ridge and lands 123cm away. How fast was the sled going when it left the ridge? 13

14 3. An Osprey (fish-eating eagle) lost its grip on a fish when it was flying perfectly horizontally back to its nest and dropped it. The Osprey was flying 105ft above the surface of the lake at the time. When the fish landed it was 43ft in front of the spot where it was dropped. How fast was the Osprey flying when it dropped the fish? 4. A ball rolls off a table that is 0.53m high. Assuming it lands 0.42m from the base of the table, how fast was the ball going when it left the table top? 5. A contractor accidentally triggers his nail gun when it is held perfectly horizontally, 1.37m above the ground. If the nail lands 337cm (be careful with units) away, how fast was it going when it left the nail gun? 14

15 4. A soccer ball is kicked horizontally off a 22.0-meter high hill and lands a distance of 35.0 meters from the edge of the hill. Determine the initial horizontal velocity of the soccer ball. a. Draw a diagram to summarize the information b. Calculate the time it takes to hit the ground c. Calculate the initial horizontal velocity 15

16 Name Date PURPOSE: LAB 1- PROJECTILE MOTION DETERMINATION OF INITIAL VELOCITY The purpose of this experiment is to determine the initial speed (muzzle velocity) of a projectile. THEORY: In order to first determine the initial horizontal speed (muzzle velocity) of the ball, it is necessary to know the horizontal distance that the ball travels and the time of fall. These quantities can be determined by shooting the ball horizontally off the table and measuring the vertical and horizontal distances through which the ball travels. From the vertical distance traveled by the ball, it is possible to calculate the time of fall. Knowing the time of fall and the horizontal distance traveled, it is possible to calculate the muzzle velocity of the ball coming out of the launcher. HORIZONTAL INITIAL VELOCITY: For a ball shot horizontally off a table with an initial speed, v 0, the horizontal distance traveled by the ball is given by: x = v o t where t is time the ball is in the air. Air friction is assumed to be negligible. The vertical distance the ball drops in time t is given by y = ½ g t 2 where t is time the ball is in the air. Air friction is assumed to be negligible. The initial velocity of the ball can be determined by measuring x and y. The time of flight of the ball can be found using: t = 2y/g and then the initial velocity can be found using v = Δx/Δt 16

17 SETUP: 1. Clamp the Projectile Launcher to a lab desk near one end of the table. 2. Adjust the angle of the Projectile Launcher to zero degrees so the ball will be shot off horizontally. PROCEDURES: 1. Put the plastic ball into the Projectile Launcher and load it to the long range position. Fire one shot to locate where the ball hits the table. At this position, tape a piece of white paper to the table. Place a piece of carbon (carbon-side down) on top of this paper. When the ball hits the table, it will leave a mark on the white paper. 2. Fire six (6) shots (more if needed). 3. Measure the vertical distance from the bottom of the ball as it leaves the barrel (this position is marked on the side of the barrel) to the table. Record this distance in Table Use a plumb bob to find the point on the table that is directly beneath the release point on the barrel. Measure the horizontal distance along the table from the release point to each of the ten dots on the paper. Record these distances in Table Find the average of the ten distances and record in Table Using the vertical distance and the average horizontal distance, calculate the time of flight and the initial velocity of the ball. Record in Table Repeat steps 1 through 6 for short and medium ranges. ANALYSIS: Vertical distance height from projectile launcher to ground) = Calculated time of flight. (show work) m t = 2y/g TABLE 1: Determining the Initial Velocity 17

18 Trial Numbers Short Distance (cm) Medium Distance (cm) Long Distance (cm) Total Horizontal Distance Average Horizontal Distance (total/6) INITIAL VELOCITY SHOW WORK BELOW (v = Δx/Δt) CONCLUSION: 18