Do Now for 4/19/13

Take out Lab reports E74,75,76HW: None

E77 Mass and Collision

• Today’s Target: I will be able to state whether or not the mass of an object has an affect on the force it applies during a collision?

• Check E74,75, and 76• Procedure check for E77• Share procedure and copy down agreed to

procedure in your lab book.• Gather data?

E77 Mass and Collision

• Share your procedure with your partners and decide which procedure and data table is the best.

• Show me for approval.• Write the agreed to procedure and data table

in your lab book. • Gather data.

Do Now for 4/22/13

• Take out E77 Materials• HW: Complete Part A from activity E78• Do something nice for the planet

E77 Mass and Collision

• Happy Earth Day!!• Today’s Target: I will be able to see if my data

supported my predictions.• Complete gathering data• Analysis 1 through 4• Key Points• Write up Activity 78• Complete Part A from activity E78

E77 Mass and Collision

E77 Mass and Collision

• 1. Did the mass of the cart affect the collision?

• Explain how you know this.– Yes, the more massive the cart, the farther the

block went.

E77 Mass and Collision

• 2. Why do you think mass did or did not have the effect you predicted?– Since the distance the block moves is an indirect

measurement of the force applied by the cart, this indicates that the more mass a moving object has, the greater the force it can apply during a collision.

E77 Mass and Collision

• 3. What part(s) of the experimental design• a. increase your confidence in the data?– Using several trials and averaging the distance the

block traveled tends to increase confidence by balancing out any errors.

• b. decrease your confidence in the data?– The use of eyes only to determine exactly where the

cart is released and where the block starts is the most obvious design flaw. Wobbling of the cart and block on the track is responsible for some error.

E77 Mass and Collision

• 4. If your car were in a collision, would you rather be hit by Vehicle 1 (2,027 kg) or Vehicle 2 (1,415 kg) from Activity 73? Explain.– All other things being equal, it would be better to

be hit by Vehicle 2 because the more massive Vehicle 1 has more potential to apply a greater force to a car.

E77 Mass and Collision

Same kind of rocks. The larger one will produce much more force in a collision!

E77 Mass and Collision - Key Points

• 1. There is a direct relationship between the mass of a moving object and the force it can apply on another object.

• 2. Good experimental design requires keeping as many variables as possible the same—except for the one being tested—so that any results can be ascribed to the variable changed.

• 3. Students should be able to design and conduct appropriate scientific investigations. This may include the use of experiments with multiple trials.