Monday 11-26 PS

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)

Calculations for the roller coaster Project paper

This is due Wednesday (Tomorrow)

Neat, typed if possible

Equations

• GPE = m g h KE = ½mv2

• a = (Vf – Vi)/t p = m v

• MA = fo / fi W = f d

• P = W / t Fnet = m a

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?

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?

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

Make up a problem

• Person

• On top of _______

• Person’s mass ______

• Amount of GPE person has ______

• Find height

Solution

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

Complete the questions on the handout in class

• Identify

• Check units

• Find the right Equation

• Plug in and solve

Homework

• Pg 858-859

• Problems 111-113, 116-125

• Due Wednesday in addition to the calculation page of the roller coaster project