SeeS

Distance How much ground an object has covered

Velocity How fast an object is going in a certain direction.

Acceleration How quickly an object slows down or speeds up.

Force A push or pull that causes an object to move, stop, or change direction. The larger the weight, the larger the force. The larger the force, the larger the acceleration.

Video The Ultimate Race!

Jet Fighter vs Car vs Motorcycle Plane passes bike at about 20 seconds [A] Car passes bike at about 25 seconds [B] Plane needs about 2000 ft to take off MOTORCYCLE: top speed 175 MPH (280 km/hr or 80 m/sec). CAR: top speed 200 MPH (325 km/hr or 90 m/sec). JET FIGHTER: top speed 1,400 MPH (about MACH 2) take off speed 200 MPH.

Jet Fighter versus Car versus Motorcycle MOTORCYCLE: Accelerates fastest off the starting line (because it is the lightest). But its top speed is only about 175 MPH (280 km/hr or 80 m/sec). CAR:Accelerates second fastest off the starting line (because it is the next lightest). But top speed is only about 200 MPH (325 km/hr or 90 m/sec). JET FIGHTER: Slowest of the starting line (it is by far the heaviest). But is accelerates for the longest time g for more than 25 seconds. But top speed MACH 2 or 1,400 MPH with a take off speed of about MPH.

Sprinter 100 m Split Times World Record & Grade 5s Sprinters accelerate fairly quickly (2 to 4 seconds) and then try and keep at that speed (velocity). World Record: 100 meters in about 9.7 s Top speed about 12 meters/second or 27 MPH Grade 5 Fastest 100 m in about 13.8 s Top speed about 8 meters/second or 18 MPH Grade 5 Fastest 100 m in about 17 s Top speed about 7 meters/second or 15 MPH but fades at end.

Sprinter 40 m Split Times World Record & Grade 5s Sprinters accelerate fairly quickly (2 to 4 seconds) and then try and keep at that speed (velocity). World Record: 40 meters in about 4.5 s Top speed about 12 meters/second or 27 MPH Grade 5 Fastest 40 m in about 6.5 s Top speed about 8 meters/second or 18 MPH Grade 5 Fastest 40 m in about 7.2 s Top speed about 7 meters/second or 15 MPH and no fade! 1

Fast Cars over a ONE MILE Drag Strip

Friction A force that happens when things rub against each other.

Gravity The force of attraction between all masses in the universe

Frequency The number of times something happens within a given time period.

Friction Supplies: Spring scales Weights String Boxes Surfaces Clamps Procedure: Clamp down the various surfaces. Connect spring scale to box with string. Place various weights in boxes. Start with box on table top (no surfaces). Pull on scale to move box with a constant velocity. Experiment with surfaces attached to boxes with binder clips and surfaces on table in many combinations. Use the readings on the scale to determine, with a given weight, how rough the surfaces are (i.e. how much friction they have). Have kids identify the roughest and smoothest surfaces and combinations. Discuss differences in force required to begin moving and keep moving, describe stationary and moving friction. What’s Happening: The rougher surfaces have more friction and require more force to overcome static and kinetic friction. Conversely, smoother surfaces require less force. Again Newton’s 2 nd law applies, the force required to move the box a constant velocity is the same as the force of kinetic friction. Notes: Teflon should be applied to the box like skis. Note the differences in the grit of the sandpaper.

Force – An action that causes a body to accelerate Friction – A force that resists motion between surfaces Static Friction – The force that resists the motion of an object while it’s at rest Kinetic Friction – The force that resists the motion of an object while it’s moving Left: Contact between surfaces Left: Static Friction Right: Kinetic Friction Friction – Kinetic and Static

Sliders Definitions: Velocity Acceleration Gravity Tension Procedure: Demonstrate spring scale measuring force (weight on the scale). Put box on cart. Attach spring scale to cart with string. Put weights in box. Pull on spring scale and see how much force it takes to make the cart do various things (constant velocity and acceleration). Replace box on cart with mystery mass and repeat the process. Guess the value of the mystery mass. Set up pulley and attach it to table, using clamp. Use weights on end of string to pull. What’s Happening: Newton's Second Law: the amount of force is directly related to the mass and the acceleration (the greater the mass, the lower the acceleration for a given force) Notes: Try constant acceleration, force, and velocity. mass cart pulley

Sliders Definitions: Velocity Acceleration Gravity Force Procedure: Put mystery boxes/weights on cart. Have kids line up and push mystery box carts. (Figure which is heaviest without lifting.) Demonstrate spring scale measuring force (weight on the scale). Attach spring scale to cart with string. Pull on spring scale and see how much force it takes to make the cart do various things (constant velocity and acceleration). Set up pulley and attach it to a table. If not the table, then to a board and attach that to the table. Use weights on end of string to pull. What’s Happening: Newton's Second Law: the amount of force is directly related to the mass and the acceleration (the greater the mass, the lower the acceleration for a given force) Notes: Try constant acceleration, force, and velocity. mass cart pulley

Pendulum An object on a wire or arm fixed to a spot. The object can then swing back and forth. They can be used for fun. Swings Amusement Park rides Desk toys They can also be used to measure time. They were used in early clocks. Grandfather Clocks Metronomes Most are powered by gravity.

Pendulum Gravity pulls down. The tension pulls towards pivot point. The resultant force makes the pendulum swing. Pendula are simple harmonic oscillators (at least at small angles θ). The natural frequency is: So the period is: The time for a full swing is only dependant on gravity and the length. That’s how grandfather clocks and metronomes originally worked. glgl √ ω = lglg √ T = 2π Pendulum Free Body Diagram TT mg ΣFΣFΣFΣF l θ

Pendula Definitions: Frequency Period Procedure: Loop ropes through basketball goal. Attach mass bob to one and mesh bag to other. Make certain they are at right angles (one swings in x and the other in y). Place chair in arc of mesh bag. Place Shotput in mesh bag. When kids arrive ask about pendula. Point out everyday pendula. Swing bob pendulum at medium height timing it. Tell kids the time, and shorten the length. Ask kids if it will take longer of shorter to swing. Repeat the swing and time. Tell the time (shorter), and length a lot. Ask kids if it will take longer or shorter to swing. Repeat the swing and time and tell (longer). Return to first middle height, remind of time. Add additional bob. Ask kids if it will take longer or shorter to swing. Swing and time, (no change). Finally one at a time have kids sit in chair. If possible have something behind their head keep it still. Bring the Shotput up to their nose and let go. It will come back very close, but not hit. What’s Happening: The total force on the mass (gravity and the rope) causes it to swing back and forth. The pendulum is a simple harmonic oscillator at small angles, with a known frequency (g/l)^.5, making it a reliable time gauge, independent of mass. The shotput part illustrates conservation of energy. The mass cannot go above its original height. Notes: Only release the shotput, DO NOT PUSH.