1. Objective 5 MOTION & FORCES

2. Have this on your desk for EVERY question involving math. FORMULAS Constants & Conversions Ruler EVERY FORMULA YOU NEED IS ON THE CHART. You won’t ALWAYS use all the numbers given. Eliminate bad answers. ALWAYS use your calculator!!!!

3. Average velocity (speed) is the change of position of an object over time. Velocity is a vector quantity that includes direction. SPEED describes how fast an object moves. Speed (v) = Distance Time

4. Acceleration Change in velocity over change in time a =final velocity – initial velocity ∆T (slope) Units for acceleration m/s/s or m/s 2

5. A 2.4 km B 2.4 m C 23 cm D 24 mm The speed of sound in human tissue is about 1600 m/s. If an ultrasound pulse takes 1.5 x 10 -5 s to travel through a tissue, what is the thickness of the tissue? TIME DISTANCE Speed = distance time 1600m/s = distance 1.5 x 10 -5 s.024m = distance

6. The table above shows experimental data collected when four cars moved along a straight-line path. According to these data, which car moved with a constant acceleration of 2 m/s 2 ? A Car Q B Car R C Car S D Car T a =final velocity – initial velocity ∆T You can immediately eliminate Q & R…WHY? A(carS) = 4m/s-2m/s = 2m/s 2s-1s 1s Use this method to check car S & car T.

7. Newton’s 1 st Law of Motion A body in motion will remain in motion. A body at rest will remain at rest. UNLESS there is a force acting on that object.

8. Newton’s 2nd Law of Motion Force = mass x acceleration

9. Newton’s 3rd Law of Motion For every action (force) there is an equal and opposite reaction (force).

10. Friction A force that acts in a direction opposite to the motion of two surfaces in contact with each other.

11. MOMENTUM The effect of motion is momentum. Momentum = Mass x Velocity

12. Work Work: amount of energy transferred by a force W = F x d The work done by forces on an object = changes in energy for that object. Work and Energy are measured in Joules 1 Joule=1 Newton meter

13. Machines use power Power: the rate at which energy is used (work is done) P=Work/time Power is measured in H.P. or watts 1 watt = 1 Joule 1 sec

14. SIMPLE MACHINES make WORK easier

15. 3 Classes of LEVERS (Resistance)

16. The human bicep muscle is a classic example of a third class lever. Similar analogies can be drawn from almost all joints in the human body.

17. % Efficiency NO MACHINE IS 100% efficient. Energy is lost as HEAT!!! %efficiency = work output X 100 work input

18. WAVES Velocity of a wave = frequency x wavelength (m/s) (Hz) (m) ν= ƒ x

19. KINETIC ENERGY- energy of motion KE= ½ (mass x velocity) 2 GRAVITATIONAL POTENTIAL ENERGY PE= mass x acceleration due x height to gravity ENERGY = mass x (speed of light) 2

20. Current = Voltage / Resistance Electrical Power = Voltage x Current Electrical energy = power x time Electricity – flow of electrical charge

21. Convection, Conduction, and Radiation Convection- Heat transfer by the mass movement of molecules

22. Convection, Conduction, and Radiation Conduction- Heat transfer by the collision of molecules that are in contact

23. Convection, Conduction, and Radiation Radiation- Heat transfer with no physical contact

24. Convection, Conduction, and Radiation.

25. PRACTICE WITH YOUR FORMULA CHART EVERY FORMULA YOU NEED IS ON THE CHART. You won’t ALWAYS use all the numbers given. Eliminate bad answers. ALWAYS use your calculator!!!!

26. Density of an object is 1.25 g/ml at 20°C and the mass is 4 g, what is the volume?

27. An object falling from the sky traveled 4000 m in 8 seconds, what is the speed of the object?

28. A car accelerates from 0 m/s to 100 m/s in 5 seconds. What is the acceleration of the car?

29. A 0.75 kg ball is thrown with a velocity of 40 m/s, what is the momentum of the ball?

30. A 25 kg rock is increasing in velocity from 0 m/s to 50 m/s in 10 seconds. What is the rock’s force?

31. If a box is moved 5 m with a force of 100 N, how much work is done?

32. How much power is the result of completing 5000 J of work in 30 seconds?

33. What is the % efficiency of a machine if the work output is 40 J and the work input is 50 J?

34. What is the kinetic energy of a 100 kg object traveling a 5 m/s?

35. What is the potential energy of a 50 kg rock sitting on top of a 75 m cliff?

36. What is the velocity of a wave with a frequency of 1000 hz and a wavelength of 0.00000045 m?