Forces and Motion Notes 4/27/2015

IMPORTANT FORMULAS TO KNOW: SPEED(m/s) = DISTANCE(m) / TIME(s) VELOCITY(m/s) = DISPLACEMENT(m) / TIME(s) ACCELERATION(m/s2) = VELOCITY(m/s) / TIME(s) FORCE(Newton) = MASS(kg) * ACCELERATION(m/s2) WORK(Joule) = FORCE(Newton) * DISTANCE (m)

SPEED SPEED = DISTANCE / TIME Constant Speed on a graph of x = time, y = distance: Average Speed = speed average for whole length of time SLOPE = RATE Rate at which distance is covered SI unit is meters/second (m/s)

VELOCITY VELOCITY = DISPLACEMENT/TIME Change in position in a given direction over time Directions: (North, South, East, West, Towards, Away) Can be represented by arrows (vectors)

ACCELERATION ACCELERATION = VELOCITY/TIME SI Units (m/s)/s simplified to become m/s2 Change in velocity over time Gravity is an acceleration: 9.8m/s2

NEWTON’S LAWS Law #1 (law of inertia) An object in motion will stay in motion and an object at rest will stay at rest UNLESS an unbalanced force acts on it

NEWTON’S LAWS Law #2 (law of action) FORCE = MASS * ACCELERATION (F=ma) An object that has an unbalanced force acting on it will accelerate in that direction of that force SI Unit of FORCE is NEWTON SI UNIT of MASS is kilogram kg SI UNIT of ACCELERATION m/s2 8 N 6 N

NEWTON’S LAWS Law #3 (law of reaction) Forces always occur in equal and opposite pairs. For every action there is an equal and opposite reaction

Work WORK = FORCE * DISTANCE SI Unit: JOULE One joule of work is done when A force of one Newton moves an object through a distance of one meter in the same direction of the force

Which of Newton’s Laws does the following best describe? 1. A golfer swings the clubs and hits the golf ball to the green.

Which of Newton’s Laws does the following best describe? 1. A golfer swings the clubs and hits the golf ball to the green. 2nd Law!!!

Which of Newton’s Laws does the following best describe? 2. The Earth revolves around the sun about every 365 days.

Which of Newton’s Laws does the following best describe? 2. The Earth revolves around the sun about every 365 days. 1st Law!!!

Which of Newton’s Laws does the following best describe? 3. A boat pulls a skier across a lake.

Which of Newton’s Laws does the following best describe? 3. A boat pulls a skier across a lake. 2nd Law!!!

Which of Newton’s Laws does the following best describe? 4. A plate stays on the table as the table cloth is ripped off.

Which of Newton’s Laws does the following best describe? 4. A plate stays on the table as the table cloth is ripped off. 1st Law!!!

Which of Newton’s Laws does the following best describe? 5. A person walks up the stairs.

Which of Newton’s Laws does the following best describe? 5. A person walks up the stairs. 3rd Law!!!

6. What is the net force and direction of movement?

6. What is the net force and direction of movement? 1 Newton to the right

7. Balanced or Unbalanced???

7. Balanced or Unbalanced???

8. The figure below shows two equal forces acting on a box 8. The figure below shows two equal forces acting on a box. The box is seen from above. In which direction will the box move?

8. The figure below shows two equal forces acting on a box 8. The figure below shows two equal forces acting on a box. The box is seen from above. In which direction will the box move? Southwest

9. Which graph to the right shows an object that is NOT MOVING? SLOPE

9. Which graph to the right shows an object that is NOT MOVING? Graph C SLOPE

10. Which graph to the right shows an object that is moving at a CONSTANT SPEED? SLOPE

10. Which graph to the right shows an object that is moving at a CONSTANT SPEED? Graph B SLOPE

11. Which of the graphs to the right shows an object that is SPEEDING UP? SLOPE

11. Which of the graphs to the right shows an object that is SPEEDING UP? Graph B SLOPE

12. Which of the graphs to the right shows an object that is moving at a CONSTANT SPEED? SLOPE

12. Which of the graphs to the right shows an object that is moving at a CONSTANT SPEED? Graph D SLOPE

13. Which of the graphs to the right shows an object that is SLOWING DOWN? SLOPE

13. Which of the graphs to the right shows an object that is SLOWING DOWN? Graph C SLOPE

14. Which of the graphs to the right shows an object that is SPEEDING UP and SLOWING DOWN back and forth? SLOPE

14. Which of the graphs to the right shows an object that is SPEEDING UP and SLOWING DOWN back and forth? Graph A SLOPE

15. Name ALL the graphs to the right shows an object that is accelerating? SLOPE

15. Name ALL the graphs to the right shows an object that is accelerating? Graphs A, B, and C. SLOPE

16. The graph to the right shows the motion of a cat over time 16. The graph to the right shows the motion of a cat over time. What was the cats average speed? AVERAGE SLOPE

16. The graph to the right shows the motion of a cat over time 16. The graph to the right shows the motion of a cat over time. What was the cats average speed? 0.8 m/s AVERAGE SLOPE

17. The graph to the right shows the motion of a cat over time 17. The graph to the right shows the motion of a cat over time. During which interval does it show the cat was moving the FASTEST? Between 0 and 40 seconds. Between 40 and 60 seconds. Between 60 and 100 seconds. SLOPE

17. The graph to the right shows the motion of a cat over time 17. The graph to the right shows the motion of a cat over time. During which interval does it show the cat was moving the FASTEST? Between 0 and 40 seconds. Between 40 and 60 seconds. Between 60 and 100 seconds. SLOPE

18. The graph to the right shows the motion of a cat over time 18. The graph to the right shows the motion of a cat over time. During which interval does it show the cat was STATIONARY? Between 0 and 40 seconds. Between 40 and 60 seconds. Between 60 and 100 seconds. SLOPE

18. The graph to the right shows the motion of a cat over time 18. The graph to the right shows the motion of a cat over time. During which interval does it show the cat was STATIONARY? Between 0 and 40 seconds. Between 40 and 60 seconds. Between 60 and 100 seconds. SLOPE

19. The graph to the right shows the motion of a cat over time 19. The graph to the right shows the motion of a cat over time. During which interval does it show the cat was moving the SLOWEST? Between 0 and 40 seconds. Between 40 and 60 seconds. Between 60 and 100 seconds. SLOPE

19. The graph to the right shows the motion of a cat over time 19. The graph to the right shows the motion of a cat over time. During which interval does it show the cat was moving the SLOWEST? Between 0 and 40 seconds. Between 40 and 60 seconds. Between 60 and 100 seconds. SLOPE

20. The graph to the right shows the motion of a cat over time 20. The graph to the right shows the motion of a cat over time. What is the cat’s average speed for the first 40 seconds of the trip? SLOPE

20. The graph to the right shows the motion of a cat over time 20. The graph to the right shows the motion of a cat over time. What is the cat’s average speed for the first 40 seconds of the trip? 0.5 m/s SLOPE

21. What is the acceleration of the above box? 45 Newtons of force 10 kilograms 21. What is the acceleration of the above box? FORCE = MASS * ACCELERATION SI Unit: NEWTONS

21. What is the acceleration of the above box? 45 Newtons of force 10 kilograms 21. What is the acceleration of the above box? 4.5 m/s2 FORCE = MASS * ACCELERATION SI Unit: NEWTONS

22. A 12x12 moving box was loaded into a moving truck 22. A 12x12 moving box was loaded into a moving truck. If it took 800 joules to get the box 5 meters to the truck, how much force was applied to the box? WORK = FORCE * DISTANCE SI Unit: JOULE

22. A 12x12 moving box was loaded into a moving truck 22. A 12x12 moving box was loaded into a moving truck. If it took 800 joules to get the box 5 meters to the truck, how much force was applied to the box? F = 160 Newtons WORK = FORCE * DISTANCE SI Unit: JOULE

23. A 12 kg ball was kicked and hit another student 23. A 12 kg ball was kicked and hit another student. The ball accelerated at 4 m/s2. How much force did the student take on impact? FORCE = MASS * ACCELERATION SI Unit: NEWTONS

23. A 12 kg ball was kicked and hit another student 23. A 12 kg ball was kicked and hit another student. The ball accelerated at 4 m/s2. How much force did the student take on impact? F = 48 Newtons FORCE = MASS * ACCELERATION SI Unit: NEWTONS

24. A student lifted a book weighing 120 Newtons off the ground 1 24. A student lifted a book weighing 120 Newtons off the ground 1.5 meters. How much work did the student do? WORK = FORCE * DISTANCE SI Unit: JOULE

24. A student lifted a book weighing 120 Newtons off the ground 1 24. A student lifted a book weighing 120 Newtons off the ground 1.5 meters. How much work did the student do? W = 180 joules WORK = FORCE * DISTANCE SI Unit: JOULE

25. A roller coaster is pulled up the first hill with a force of 225 N 25. A roller coaster is pulled up the first hill with a force of 225 N. It uses 18,000 joules of energy to get the roller coaster up the hill. How tall must the first hill of the roller coaster be? WORK = FORCE * DISTANCE SI Unit: JOULE

25. A roller coaster is pulled up the first hill with a force of 225 N 25. A roller coaster is pulled up the first hill with a force of 225 N. It uses 18,000 joules of energy to get the roller coaster up the hill. How tall must the first hill of the roller coaster be? d = 80 meters WORK = FORCE * DISTANCE SI Unit: JOULE

26. Tommy hit a golf ball with a force of 1125 Newtons and it gave the ball an acceleration of 45 m/s2. What is the mass of the golf ball? FORCE = MASS * ACCELERATION SI Unit: NEWTONS

26. Tommy hit a golf ball with a force of 1125 Newtons and it gave the ball an acceleration of 45 m/s2. What is the mass of the golf ball? m = 25 grams FORCE = MASS * ACCELERATION SI Unit: NEWTONS