Physics Review

1. Physics Review Kyrielle Lord, Claire Gotfredson Per. 3

2. Scientific Method Question- How does weight affect the speed of an object falling? Prediction/ hypothesis- The heavier the object, the faster it will fall. Experiment- Drop objects of different masses from the same height. Results- Record data in a table and graph the results. Analyze data- Compare graphs. Adjust ideas accordingly- Determine if results support your prediction and change thinking accordingly. • Helps one to conduct skydiving experiments and improve calculations

3. Motion Graphs • helps one to visualize the outcome of a skydivers path

4. Calculations Average Velocity- change in distance/ change in time→ distance fallen over time it takes to fall Instantaneous Velocity- 2 times average velocity→ if the object starts at rest and has a uniform acceleration, multiply average velocity by 2. If doesn't start at rest, 2 times average-initial velocity Acceleration- change in velocity/ change in time→ velocity final-velocity initial over final time-initial time (m/s ^2) • Helps skydiver to know their speed and acceleration when diving

5. Newton’s 1st Law (Fnet) • If net force equals 0, forces are balanced and motion will continue at a constant velocity. (When parachuter hits terminal velocity) • If net force is not 0, forces are unbalanced→ acceleration, change in speed or direction • When skydiver accelerates to terminal velocity→ diver keeps falling until comes in contact with the floor

6. Free Body Diagrams • Show air resistance, gravity and other forces of skydiver, along with the net force

7. Newton’s 2nd Law (Fnet= ma) • acceleration is directly proportional to the net force exerted • If net force is constant, mass and acceleration are inversely proportional • Mass= kilograms, Force= newtons, Acceleration=m/s • Skydiver uses mass and force to determine their acceleration when falling

8. Weight Weight= the force of gravity Weight doesn't equal mass (mass is the amount of matter in an object) Fg= ma (gravitational acceleration is 9.81) • weight acting on skydiver is independent for each diver and two divers are affected by gravitational acceleration and fall at the same speed, despite their different weights

9. Law of Gravitation Gravitational force exists between 2 objects Gravity is directly proportional to mass Gravity is inversely proportional to distance Fg= G m*m2 / r^2 • distance between plane and diver or ground and diver affects gravitational force between them

10. Momentum, impulse, collisions Momentum (p)= mass* velocity Impulse changes momentum ( fast /slow) Impulse (j)= force* time Extending the time of impact decreases the impact Momentum is always conserved→ elastic and inelastic (sticks) collisions: Elastic= (m*vi)+(m2*vi)= (m*vf)+(m2*vf) Inelastic= (m*vi)+(m2*vi)= (m+m2)vf • Momentum and impulse help diver to avoid collisions and use parachute to improve safety

11. Energy (KE,GPE) GPE=mass*gravitational acceleration*height above ground→ gravitational potential energy is greater when higher KE=1/2mv^2→ when an object is in motion, as an object falls GPE turns into kinetic energy Velocity of a free falling object is the sqrt*(2*g*height fallen) Units:joules Energy is conserved and is the ability to produce work • skydiver starts with a lot of GPE and turns into KE as he falls

12. Thermodynamics Temp: avg kinetic energy of molecules (faster molecules=more KE=higher temp) Thermal energy: energy of an object resulting from motion of all its molecules (volume*temp) Heat energy always transfers from high KE//concentration to low KE//concentration Input=work+output Pressure increases as temp increases be molecules are moving faster, gas pressure depends on temp, container size, #of molecules • Temperature of body heat and weather in the sky helps determine