Physics 11

Force Diagrams

Mr. Jean

The plan:

• Video clip of the day

• Force Diagrams

• Friction

• Friction Practice Questions

Net Forces:

• The existence of an unbalanced force for a given situation can be quickly realized by looking at the free-body diagram for that situation.

Brightstorm Videos:

• Net Forces: http://www.brightstorm.com/science/physics/newtons-laws-of-motion/net-force-resultant-force/

• http://www.youtube.com/watch?v=AFnoBrhOR4U

Consider the following forces:

Consider the following:

Solutions:

Determine the Net Forces:

Solutions:

Determine the acceleration if the object had a mass of 2kg:

Solutions:

Practice Questions:

• P. 144– Question #5 & #6

• Upcoming items: – Rocket Design Day #1 Thursday

• Research & Introduction

– Quest Assignment #4 due next Sunday

Rocket Design Information:

The Engines:

Rocket Build Goals:

• Nose Cone test

• Wing test

• Parachute Test

• Engine Size Test

Nose Cone Test:

• A proper nose cone must fit inside the rocket fuselage.– The fit should be snug– Nose cone should detach from body when an

individual quickly blows air through the body. • Do not have your parachute in when testing this!

Wing Test:

• In order to test the strength of the wings. A individual should be able to hold the entire rocket by one wing.– If the wing becomes unglued, falls off or

structurally fails this rocket is not suitable for flight.

Parachute Test:

• Take a 100g weight and attach parachute to it. Drop from ceiling with parachute fully open. The parachute should guide the weight softly to the ground without horizontal displacement. – Common Failures

• Parachute lines break• Parachute causes horizontal motion• Issues with parachute design

Engine Test Part #1:

• Engine should have a snug fit to the inside of the fuselage. – There MUST be a point where the engine can

not go past. • However there must remain hollow space to allow

the parachute deployment charge to function correctly.

– Engines are NOT to be glued into the rocket.

Engine Test Part #2

• Engines should be secured to make sure that when deployment charge explodes it does not fire the engine out the back of the model. – Rockets MUST HAVE some type of engine

harness preventing the engine from falling out the bottom end.