MATERIALS Ramp Masking tape Meter stick Ball/ marbles (1 to 5 cm diameter) PRE-LAB PROBLEM: A ball is thrown horizontally from the roof of a building 7.5m tall and lands 9.5m from the base. a) Draw a diagram to depict the scenario? b) What was the ball's initial speed?Read aloud + 2 of 6 PART 1: FINDING THE HORIZONTAL VELOCITY 1. Set up a low ramp made of hot wheel tracks on a table so that a ball can roll down the ramp, across a short section of table, and off the table edge as shown in Figure 1. 2. Ensure that the track is not tilted but fixed firmly to the stand. 3. Set a low angle for the ramp, so that your horizontal velocity is not too high. Measure time that the ball is rolling on the horizontal portion of the table. 4. Two people will note the time when it first reaches the end of the ramp and travels horizontally to the end of the table. Average the time. Take three trials for each run. Precision in time measurement is of utmost importance. (t) 5. Practice catching the ball before it leaves the table. 6. Mark a starting position on the ramp with masking tape so that you can repeatedly roll the ball from the same place. . Note: Do not let the ball hit the floor. Catch the ball as soon as it leaves the table. 7. Measure the distance from the end of the ramp to the end of the table. (d) 8. The Horizontal Velocity can then be calculated by: Distance on the table (horizontal section only) - .........cm = ..........m Trial Time 1 Time2 Average t ( secs) Trial 1 Trial 2 Trial 3 Average of all Horizontal velocity =Vx = (distance travelled on the table)/t =d/t = ........... m/s9. Measure the distance from the table top to the floor and record it as the table height h in the data table. Use a plumb bob or meter rod to locate the point on the floor just beneath the point where the ball will leave the table. Mark this point with tape; it will serve as your floor origin. plumb bob floor origin Figure 2 10. Use the measured height of the table to determine the time it takes the ball to land on the floor. Since the time is determined by the vertical height, use the following equation for vertical motion. Show your work below. Hint #1: The distance must be in meters. Hint #2: Since the ball rolls horizontally off the table, the initial vertical velocity is zero. Think then what is the initial velocity. Hint #3: Since the ball falls due to the force of gravity only, the vertical acceleration is the acceleration due to gravity, -9.8 m/s'. Since horizontal velocity stays constant, what is the value of the horizontal acceleration?Projectile Motion Lab 14. Use your average velocity value to calculate the distance from the floor origin to the impact point where the ball will hit the floor, using the equation below. Ax = v.I Hint #1: The time the ball takes to fall is the same as the time the ball flies horizontally. Hint #2: Your calculated distance is in meters. 12 Mark your predicted impact point on the floor with a target spot at the predicted impact point. Be sure the impact point is along the line of the track. Use chalk to mark the position. If your instructor can provide a carbon paper that would be better. 13. After your instructor gives you permission, release the ball from the marked starting point, and let the ball roll off the table and onto the floor. Measure the distance from the floor origin to the actual impact point and enter the distance in the data table. IF YOU MISS THE SPOT your calculations are probably incorrect. Recalculate and try again.13. After your instructor gives you permission, release the ball from the marked starting point, and let the ball roll off the table and onto the floor. Measure the distance from the floor origin to the actual impact point and enter the distance in the data table. IF YOU MISS THE SPOT your calculations are probably incorrect. Recalculate and try again. DATA TABLE: TABLE:1 TABLE:2 Trial Velocity (m/s) 1 Average velocity m/s Table height m W N Predicted impact point m Actual impact point distance m 10ANALYSIS 1. Did the ball land farther from or closer to the table than your predicted position? 2. You were not able to account for air resistance in your prediction. If air resistance were not present, would the ball land farther from or closer to the table? Why? 3. Does your observation of the ball's actual landing point make sense when you consider the effect of air resistance? Why or why not? 4. Find the % error between the predicted and actual impact distances. oerror = actual - predicted - x100 actual