Forces and Motion Practicals Flashcards
investigating the motion of everyday objects (tennis ball):
- equipment needed
- method
- evaluation
- safety measures
equipment:
- tennis ball
- stop watch
- metre rule
method:
1. measure out a known height using the metre rule
2. drop the object (tennis ball) from this known height, which represents the distance travelled
3. use the stop clock to measure how long the object takes to travel this distance
4. repeat this three times and calculate an average
5. then repeat all steps for a range of heights
6. make a table of results and calculate speed using speed = distance/time
evaluation:
- make sure the measurements on the metre rule are taken at eye level to avoid parallax error
- take into account human reaction time and to reduce this significance, larger distances could be used to result in larger time intervals
- using a ball bearing and an electronic data logger would remove human reaction time
- light gates can obtain highly accurate measurements of time
- ensure the experiment is not done where there is a breeze as this could affect the motion of the falling object
safety:
- place a mat or soft material below any falling object to cushion its fall
investigating the motion of everyday objects (toy car on a bench):
- equipment needed
- method
- evaluation
- safety measures
equipment needed:
- toy car
- metre ruler
- string
- bench pulley
- mass hanger and masses
- stop watch
- masking tape
method:
1. attach bench pulley to the end of the bench
2. secure mass hanger to string and attach it to toy car
3. mark the cars position with masking tape to make the end mark and then pull the car back so the mass hanger is raised to make the start mark
4. use the metre ruler to measure the distance between the start and end markers
5. release the car from the start mark and start the stop watch, then when it reaches the end mark stop the timer
6. repeat and calculate and average
7. use speed = distance/time to find the speed
evaluation:
- make sure the measurements on the metre rule are taken at eye level to avoid parallax error
- light gates can be used to obtain highly accurate measurements of time
- take into account human reaction time
safety measures:
- place a mat or soft material below any falling object to cushion its fall to prevent it landing on your feet and causing injury
investigating how extension varies with applied force:
- equipment needed
- method
- evaluation
- safety measures
equipment needed:
- clamp and stand
- known masses
- spring
- rubber band
- ruler
- G-clamp
method:
1. use the ruler to measure initial length of the spring when no force is applied
2. add a mass to the end of the spring and measure extension
3. add different masses and measure the extension
4. plot a graph of force applied against extension of the spring (force can be calculated by 10 x the mass on the spring)
evaluation:
- ensure all measurements are taken from eye level to avoid parallax error
- ruler should be vertical and can be attached to clamp stand to avoid it moving
- use a fiducial marker to accurately read extension
- use of ruler with finer calibrations
safety measures:
- ensure goggles are worn during the experiment in case the spring or rubber band snaps
- use a G-clamp to secure the clamp stand to the desk so the clamp and masses do not fall and cause injury
