Describe an Accurate Method for calculating the Terminal Velocity of a Sphere.(4)
*Place 2 or more Rubber Bands on the Measuring Cylinder far enough down the cylinder at an Equal Distance, so that Terminal Velocity will have been Reached.
*Measure the time for the Sphere to fall a given Distance using a Stopwatch and measure the Distance using a Metre Rule.
*Repeat this 3 times to calculate an Average Velocity and remove anomalies.
*Calculate Terminal Velocity by dividing Distance between markers by the Average Velocity between Markers.
Explain why a Larger Sphere would Increase the Percentage Uncertainty of Calculated Terminal Velocity.(4)
*Larger Sphere=Larger Weight
*Therefore a Greater Terminal Velocity.
*However, as Terminal Velocity increases, Time taken decreases.
*Absolute Uncertainty remains the Same in Time Taken.
Describe a Method to Determine the Young Modulus of a Wire.(5)
*Set up the Apparatus.
*Measure the Diameter of the Wire and Take an Average.
*Measure the Unstretched Length between fixed end and Marker.
*Increase the Weight in equal intervals and measure the extension between Markers.
*Continue until Wire Snaps.
Describe how to Manipulate the Results Collected to Calculate Young Modulus.(2)
-Plot a Graph of Stress (Force x Cross-Sectional Area) against Strain (Change in Length divided by Length).
-Young Modulus will be the Gradient.
State a Hazard, its’ Risk and a Safety Precaution in the YM Experiment.
Wire could Snap causing Injury to Eyes, so wear Safety Goggles.
Improvement 1- To Prevent Uncertainty of Measurements… What do I do?
Ensure the Length of the Original wire is as Long as Possible.
State a Hazard, its’ Risk and a Safety Precaution of the YM Experiment.
When Wire snaps, Masses will fall to Floor and could cause Injury to feet. Therefore, place a Tray with Cushioning to absorb the Impact.
Improvement 2 - To Prevent Inaccurate Measurements in Final Length, What do I do?
Wait for Necking to Finish.
Improvement 3 - To avoid Parallax Error when Measuring Extension, What do I do?
Use a Reference Marker.
Describe an Accurate Method for Calculating the Viscosity of a Liquid. (7)
-Zero Balance and Measure the Mass of Set Volume of Washing Up Liquid.
-Calculate Density using M/V
- Measure the Mass of the Ball Bearing using a Balance.
-Measure the Diameter of the Ball Bearing using a Micrometre (Do this several times to Calculate a mean and Ignore Anomalies).
-Place Elastic Bands 10cm apart on the Measuring Cylinder.
-Start the Stopwatch as the Ball hits the top of the Liquid and Lap stopwatch as it Reaches the Bands.
-Repeat to Calculate a Mean.
State the Final Equation to find the Viscosity of a Liquid.
2ar^2(Ps-Pl)/9V
2 x Acceleration x Raduis^2 x (Density of Ball - Density of Liquid) / 9 x Volume
State a 2 Hazards, its’ Risk and Safety Precautions in the Viscosity of a Liquid Practical.
Spillages of Liquid can injure eye or cause an Allergic Reaction, so wear Goggles and Gloves.
Improvement 1 - To reduce Percentage Uncertainty, What do I do?
Increase the Distance between the Elastic Bands.
Improvement 2 - To reduce Uncertainty in Measuring Time, What do I do?
Use Light Gates.
Improvement 3 - If Ball Flows close to the Wall of the Measuring Cylinder, What do I do?
Repeat as the flow is no longer Laminar.
