December 14

Physics

A train car (mass=1000 kg) rear ends a stationary boxcar (mass = 5000 kg). After the collision they stick together and move at 5 m/s. What was the velocity of the 1000 kg train car before?

Objective:

To analyze our dart lab data.

Success criteria:

• Calculate the velocity of the dart before collision

• Examine the data for precision

• Justify the answer

• Evaluate the lab for possible errors

• Suggest improvements to the lab

Lab: Tailgated by a dart

Tail gated by a dartProblem: what is the velocity of the dart

before it hits the car?

Hypothesis: I believe that the dart goes -----m/s before it hits the car.

Procedure: sketch a diagram

Data table:– Mass of car– Mass of dart– Velocity of car + dart after

Calculate: Obtain a numerical answer showing the relevant

stages in the working.

Calculate the velocity of the dart before collision

Before crash After

(Dart )vd = (dart + car)v’

Examine: Consider the lab in a way that uncovers the

assumptions andinterrelationships of the lab.

Examine the data for precision

(Max – Min) / 2 x 100

Average

Examine the lab for assumptions

Examine the lab for interconnections (what depends on what?)

Justify: Give valid reasons or evidence to support your

answer.

Justify the answer

Show how your answer makes sense

• Is the answer realistic?

• Why, why not?

• How could you tell?

Evaluate: Assess the implications and limitations; make judgments about the

ideas,works, solutions or methods in the lab.

Evaluate: Assess the limitations of the lab, and make

judgments.

• useful features of lab

• Limitations of lab

• Is this lab valuable to do?

Suggest: Propose a solution, hypothesis or other possible

answer.

Suggest better:

• Procedure

• Equipment

• Measurement

• Etc.

Out:

Suggest a whole new lab that would address the same concept: