Monday 11-26 PS

Homework

• Pg 858-859

• Problems 111-113, 116-125

• Due Wednesday

Conversions

• Divide your gram (g) mass value by 1000 to determine the kilogram (kg) value

• Divide your speed in (km/hr) by 3.6 to get the speed in (m/s)

• (kJ) means kilojoules. Multiply the number of (kJ) by 1000 to get the value of energy in (j)

Write-up for Roller Coaster Project

Discussion

General information

• Write up section is due Tuesday

• Neat, typed if at all possible

• All answers must be completed in sentence form

• Define the concepts asked in question, base your question on those definitions

• Sketch may be on different paper, but have all measurements, velocity, GPE and KE information

Question #1

• What Simple machines can be connected to the construction or operation of your roller coaster?

Question #2, #3

• Produce a sketch (not a photocopy of some person’s sketch)

• Indicate height values to every important point on the coaster (In meters)

• Accurate line representing the track

• IF your group filmed your coaster and you can e-mail the results, I will try to get it up on the web-site

Question #4

• Circle what was successfully completed on the 2 best runs on the track

• Describe, in detail, the special section(s)

Question #5

• Get signatures from Me, if you have completed your runs

• Add the date on which the runs were performed

Question #6

• Does the ball accelerate during the entire roller coaster run?

Question #7

• Indicate on your sketch, the point of greatest velocity of the ball during the run.

• If you can’t decide between two label and explain both

Question #8

• Draw a free body diagram of the ball as it rolls down the first slope.

• Arrows , direction

• Label forces

Question #9

• Does the track exhibit any evidence of gaining elastic potential energy during the movement of the ball over it, during a run?

Question #10

• Indicate where does the ball has its most and least amount of GPE during its run on your sketch?

Question #11

• Indicate where the ball has its most and least amount of KE during its run on your sketch

Question #12

• Indicate the relationship between the amount of GPE and KE the ball has as it moves up a hill on the track

Question #13

• Does the ball possess the same amount of energy at the end of the run as it had in the beginning?

• Forms of energy

• Conservation of energy

Question #14

• If you make your hill too steep, the ball will fly off the top of it . Why does this occur

• Inertia

• Momentum

• Newton’s laws

Calculations for the roller coaster Project paper

• This is due Wednesday

• Neat, typed if possible

Equations

• GPE = mgh• KE = ½mv2

• a = (Vf – Vi)/t• p = mv• MA = fo / fi • W = f d• P = w / t

Question #15

• Calculate the GPE at start

• What is the mass of your marble?small metal = 28.3 g clear glass = 8.5 gswirled glass = 6.0 g big metal = 67 gwood = 2.0 g

What is acceleration due to gravity on Earth?

What is the height?

Question #16

• Calculate the GPE at the bottom of the first hill

Question #17

• What is the difference in the amount of GPE in the problems 15 and 16?

Question #18

• If the all of the ball’s energy lost from GPE was converted into KE at the bottom of the first hill, what is the velocity of the ball?

Question #19

• What is the acceleration of the ball from the start to the bottom of the first hill, if it takes 5 seconds to travel between points

• Initial velocity ?

• Final velocity ?

Question #20

• What is the momentum of the ball at the bottom of the first hill?

Question #21

• What is the change in GPE of the ball from the start to finish of the roller coaster ride?

Question #22

• How much energy of the ball was lost due to friction and sound by the end of the roller coaster?

• What else could take away some of the ball’s energy?

The rest of this week we will concentrate on the equations

• Steps to solving a problem using an equation

1) Identify what is given

2) Identify what is wanted

3) Make sure all values are in correct units (kg, m, s , N, J, W)

4) Identify equation that relates the givens to what is wanted

5) Plug in givens

6) Solve for what you want

Question

• A high jumper jumps 2.04 m. If the jumper has a mass of 67 kg, what is his gravitational potential energy at the highest point of the jump?

What is given?

• 2.04 m

• Height at highest point of jump

• 67 kg

• Mass of person

What is wanted?

• What is his gravitational potential energy at the highest point of the jump?

• GPE

What equation to use

• Need to connect GPE with mass and height

• GPE = mgh

• G is the acceleration due to gravity

• G is constant on earth’s surface = 9.8 or 10

Plug in and solve

• GPE = m g h

• GPE = (67) (10) (2.04)

• Around 1300 J

• The units are the units for energy, which can be used if all else is measured in m, kg, and s

Question #2

• A rock is rolling down a hill with a velocity of 4.67 m/s. It has the kinetic energy of 18.9 kJ. What is the mass of the rock?

Givens

What is wanted?

Check the units

What equation will you use to connect them?

Plug and solve

Question

• A team of horses is hitched to a cart. The team pulls with a force of 471 N. The cart travels 2.3 km in 20 minutes. Calculate the work done on the cart and the power delivered by the horses.

Horse problem

Scientific Notation

• A method used to write very large or very small numbers in a more manageable way.

• 15000 = 1.5 x 104

Write in scientific notation

• The planet of Saturn has a mass of

568 500 000 000 000 000 000 000 000 kg

In 1997, 70 294 601 planes either took off or landed at Chicago’s O’Hare airport