Solve the following equation for t: Pre-class Monday 1-23-12 Solve the following equation for t: Vf = Vi + at

PHYSICS Give back test and go over it Algebra review Covering 2 chapters this week (they are closely related) Begin ch 4: Forces BIOLOGY CHEMISTRY

What is the mascot for James Clemens’ high school? Pre-class Tuesday 1-24-12 What is the mascot for James Clemens’ high school?

NEWTON’S FORCES What is a force? Newton’s 3 Laws of Motion Push or pull exerted on an object Vector Variable: F Newton’s 3 Laws of Motion

NEWTON’S FIRST LAW An object at rest tends to stay at rest. An object in motion tends to stay in motion in a straight line unless acted upon by an external force.

NEWTON’S SECOND LAW F = m a

F = m a FORCE F : force (Newtons, N) m : mass (kilograms, kg) a : acceleration (m/s2)

NEWTON’S THIRD LAW For every action there is an equal and opposite reaction.

Launching Force Project Objective Apply the equations of motion and Newton’s Laws Materials 2-L bottle Cardstock, tape, scissors, etc. Deadlines Construct in-class by Friday Launch next Monday

Pre-class Wednesday 1-25-12 How much force is required to accelerate a 10 kg mass at 5 m/s2? Hint: use THE equation from friday

f Types of Forces T W

W = m g WEIGHT W : weight (Newtons, N) m : mass (kilograms, kg) g : acceleration of gravity (9.8 m/s2)

SF=ma Net Forces The total forces acting on an object Draw free-body diagram to show forces Ignore external forces Keep X and Y directions separate SF=ma

Examples of Free-body Diagrams

Lego My Car Procedures Materials Lego kits Spring scales Masses Using the Lego kit, build a simple car or truck. Be sure it is large enough to hold some small masses and a place to attach the spring scale. Place the car on a level surface. Attach the spring scale to it. With a constant velocity, pull the car along the ground with the spring scale. Record the value of the force. Change the weight of the car by adding more masses. Repeat 3 times. Based on your results, what is the relationship between weight and applied force? Materials Lego kits Spring scales Masses

How much does a 10 kg mass weigh? Pre-class Thursday 1-26-12 How much does a 10 kg mass weigh? Hint: use one of the equations from yesterday

Terminal Velocity The maximum speed that can be obtained by a falling object The force of gravity is equally balanced by the air resistance force (drag) Constant speed, no acceleration

Measuring Effects of Air Resistance Materials Meter stick Paper Stopwatch Scissors Procedures Drop a flat piece of paper 2 m. Measure the time for it to fall. Crumple the piece of paper into a loose ball. Measure time to fall in 2 m. Crumple the piece of paper into a tighter ball. Measure time to fall 2 m. Use the scissors to design your own paper object. Type Time (s) Flat paper Loosely crumpled Tightly crumpled Your design What characteristic of the paper affected the falling time the most?

CH 4 HW (p113-115) 59. -9.8 N 61. 6,900 N 64. 250 kg 65. balloon, basketball, shot-put (b. reverse) 70. 250 N, bag does not hold 73. -14 m/s, 3185 N Top to bottom: 45 N, 57 N, 93 N 82. 138 m 89. 9.8 m/s2, 98 m/s, -49 N, 10 s 92. 37 N, 2.4 m/s2

Pre-class for Wednesday 8-22-07 Identify the forces on the crate by drawing a free-body diagram. Be sure to label each force and show its direction.

CHAPTER 4 &5 EQUATIONS SF=ma W = m g f = m FN F = ma FN

EQUILIBRIUM Take attendance Give back graded work Go over home work problems Finish chapter If time, work on homework

Lego My Car Procedures Materials Using the Lego kit, build a simple car or truck. Be sure it is large enough to hold some small masses and a place to attach a rubber band. Place the car on a level surface. Cut and attach a rubber band to it. Determine the length the rubber band stretches to get the car moving. Change the weight of the car by adding more masses. Determine the length the rubber band stretches in moving the car. Repeat 4 times. Without actually performing the experiment, describe for me (Be specific!) how you would determine the force needed to move the car. Materials Rubber bands Lego kits Ruler Masses

TEST OVER CHAPTER 5 Take the time before the pep rally to study (about 20 minutes) turn in homework before you leave for pep rally return to this room, then we will go next door