TP Physical Science Practice: Position/Velocity/Acceleration/Force Diagrams & Newton's Laws/Momentum
Objects in Motion
70 Mass of Object A = 2 kg 60 Mass of Object B = 4 kg
Object A
Object B
50
Velocity (m/s)
40
30
20
10
0 0 5 10 15 Time (s) 20 25 30
How fast was Object A going at t=15 seconds? Which object slowed down, and when? (t=? to t=?) What is the acceleration of Object B from t=20 to t= 25 seconds?
If the last few points indicate a trend, how FAST will Object A be going at t=30sec? Remember that v=d/t. How far did Object A go from t=20 s to t=30 seconds?
How much does Object A WEIGH? (Use your notes or 13-4)
How much momentum does Object B have at t=7seconds?
Draw a force diagram for a 5 kg vehicle traveling at a CONSTANT 2 m/s on the floor. Label all the forces' names. Calculate numbers for Fg & FN. If Friction exerts 3.0 N of force, how big is the applied force?
Draw a force diagram for a 5 kg vehicle ACCELERATING along the floor. Label all the forces names. Calculate numbers for Fg & FN. Assume friction still exerts 3.0N of force – now how much is the applied force?
Experiment Design – Making "Tests" Two people are trying to find out how effectively a new grease reduces friction. Their experiments are described below. W's Experiment: I put grease on a table. Then I used a digital computerized meter to measure the amount of friction between a block and the table. I repeated this ten times and always got the same number. Z's Experiment: I put a block on the table and measured the friction between the table and the block using a cheap spring scale. I repeated this three times and got almost the same number each time. Each time, I put the block in the same place on the table. Then I put the grease on that part of the table. I measured the friction between the block and the table three more times, using the same spring scale.
What is the independent variable in this experiment?______________________ What is the dependent variable in this experiment?_____________________ What other quantities could affect the results & should be kept constant?
What SHOULD the data table look like?
Which person has a better experiment & why?