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Acceleration is a change in ______________ or ___________________. - Acceleration includes:

Acceleration is a change in ______________ or ___________________. - Acceleration includes: - starting - stopping - slowing down - speeding up - changing direction Speed or direction.

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Acceleration is a change in ______________ or ___________________. - Acceleration includes:

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  1. Acceleration is a change in ______________ or ___________________. - Acceleration includes: - starting - stopping - slowing down - speeding up - changing direction Speed or direction

  2. An object traveling at a constant speed does/does not accelerate because its speed does/does not change.

  3. 3. What is the acceleration of the car between 4 and 6 seconds? There is no acceleration; the car is moving at a constant speed. Since acceleration is a CHANGE IN SPEED, no acceleration occurs.

  4. The formula for average speed is D S T Distance divided by time (D/T)

  5. What is the average speed of the car after 5 seconds? D=25m; T=5s; S=D/T=25/5=5m/s

  6. Car A Car B What is the average speed of car A after 3 seconds?

  7. Distance = 30m; • Time = 3s • Speed = D/T = 10m/s

  8. . Match the graphs below to the statements. A car traveled 50 m at 40 km/hr, then traveled 20 m at 30 km/hr 8. A car traveled 50 m at 30 km/hr, then traveled 20 m at 40 km/hr

  9. . Match the graphs below to the statements. A car traveled 50 m at 40 km/hr, then traveled 20 m at 30 km/hr B – 40 is faster than 30, so the 1st part of the line is higher than the second part of the line, showing greater speed.

  10. . Match the graphs below to the statements. 8. A car traveled 50 m at 30 km/hr, then traveled 20 m at 40 km/hr A – The car traveled 30km/hr first, then accelerated to 40 km/hr. The lower line representing 30km/hr is first, then goes up to 40km/hr

  11. Match the graphs below to the statements. 9. A car decelerated (slowed down) from 40 km/hr to 30 km/hr, then traveled 30 m 10. A car traveled at 30 km/hr for 50 m, then accelerated

  12. Match the graphs below to the statements. 9. A car decelerated (slowed down) from 40 km/hr to 30 km/hr, then traveled 30 m D – the car was going faster at first, so the line starts higher on the speed axis, then drops

  13. Match the graphs below to the statements. 10. A car traveled at 30 km/hr for 50 m, then accelerated C – the car traveled a constant speed, then sped up, so you have a flat line followed by a slant upwards as speed increases

  14. A – No motion occurs—the forces push equally, so nothing moves 11. When two forces are balanced: A. No motion occurs B. The object accelerates C. The object continues in the same direction as before

  15. When an object is acted on by unbalanced forces, what ALWAYS happens? A. No motion occurs B. The object continues in the same direction C. The object accelerates D. The object stops While an object may stop because of unbalanced forces, it will not ALWAYS stop. However, it will ALWAYS accelerate—change direction or speed.

  16. 13. What is the net force in the system below? 4 N 8 N 8N – 4N = 4N left Arrows moving in opposite directions are subtracted. The object moves in the direction of the greater force.

  17. 14. What is the net force in the system below? 12 N 10 N Arrows going the same direction are added. The net force is the sum of all forces working on the object. This will move to the right with a force of 22N

  18. 15. Draw the graph for the following statement: A roller coaster going down a big hill. Speed (km/hr) Distance

  19. The roller coaster will gain speed as it goes downhill because of the acceleration of gravity. Towards the bottom of the hill, it will be moving fastest Speed (km/hr) Distance

  20. 16. Draw the graph for the following statement: A pitcher throwing a baseball. Speed (km/hr) Distance

  21. The ball is going fastest when it leavesthe pitcher’s hand. It slows down the farther it goes, covering less distance asit slows and eventually reaches 0 distance (hits the ground). Speed (km/hr) Distance

  22. 17. Draw the graph for the following statement: A car traveling from one stop sign to the next. Speed (km/hr) Distance

  23. A. The car is sitting still; it has traveled no distance.B. The car increases speed and distance.C. The car reaches 30 km/hr for a while.D. The car slows down and comes to a stop. Speed (km/hr) C B D A Distance

  24. 18. For an experiment, the materials required are: toy car meter stickramp weightsstopwatch The objective of the experiment is probably to: • Test how friction affects the speed of the car • Test how the angle of the ramp affects the speed of a car • Test how mass affects the speed of the car C. Test how mass affects the speed of the car

  25. 19. Explain how each item would be used in the experiment you chose in number 17.toy car meter stick stopwatch ramp weights The toy car would be released down the ramp. The stopwatch would be used to time how long it takes to reach the bottom. The weights would be used to change the mass of the car, thus testing to see how mass affects the speed of the car.

  26. 20. If a car travels East at 60 mph, then changes direction and travels northeast at 60 mph, what happens to • its speed? The speed remains 60mph, so the speed does not change. • Its velocity? The car changes direction. Velocity is speed AND direction, so the car changes VELOCITY when it changes direction. Therefore, the velocity of the car changes.

  27. 21. A racecar is traveling around a track at a constant speed of 200 miles/hr. Which point on the track is it accelerating? Explain why/why not.

  28. The racecar accelerates only at point B. * Since the car is traveling at a constant speed, the only change is in direction. * The car changes direction at B as it goes around the curve, so acceleration occurs only at B.

  29. 22. The race car is traveling at a constant speed of 200 mi/hr all the way around the track. Explain why its velocity is different at each point A, B, and C.

  30. Velocity is speed + direction.A is going East.B is turning.C is going West.Although the speed is the same at A, B, and C, the direction is different at each point, so the velocity is different at each point.

  31. 23. What is the difference between speed and velocity? Make a Venn diagram Direction Distance over time Speed Velocity

  32. 23. What is acceleration? And how do you calculate it? Acceleration is a change in speed or direction (speeding up, slowing down, stopping, starting, changing direction) Acceleration = F/m F m a

  33. 24. A 4000 kg truck and a 1000 kg car are racing. 10,000 N of force is applied to each of them. What will be the acceleration of the truckand of the car? Remember, if F = ma, then A = F/m - The truck’s acceleration will be _______ - The car’s acceleration will be _____ Which will accelerate faster and by how much?

  34. 24. A 4000 kg truck and a 1000 kg car are racing. 10,000 N of force is applied to each of them. What will be the acceleration of the truckand of the car? Remember, if F = ma, then A = F/m - The truck’s acceleration will be a = F/m aTRUCK = 10,000N/4000kg = 2.5 m/s2 - The car’s acceleration will be aCAR = F/m a = 10,000N/1000kg = 10 m/s2 Which will accelerate faster and by how much? The car will accelerate faster (because it is lighter) by 10m/s2 - 2.5m/s2 = 7.5m/s2

  35. 25. One of the laws of motion states, “Things in motion stay in motion unless an unbalanced force acts upon it.” When a marble is rolled across the floor, what is the unbalanced force that causes it to slow down and stop? Friction!!

  36. 26. Explain why a hailstone falling from 50 m will hurt a lot worse than a hailstone falling from 10 m if it hit you. (Remember, agravity = 9.8 m/s2) The farther it falls, the faster it moves because of the acceleration of gravity. The faster moving hailstone from 50 m will hurt more than the slower hailstone that has only fallen 10m.

  37. 27. Calculate the force needed to accelerate a mass a 3000 kg mass at 6 m/s/s acceleration. (Hint: F=ma) F=ma F=3000kg x 6ms/s/ D = 18,000N m a

  38. 28. Place the following statements in the correct space: • A Shows how fast an object is moving • B shows direction • C shows change in speed • - D shows change in direction Direction How fast Change in speed Change in direction

  39. 29. In an experiment that you drop a ball from different heights to determine how the height affects the speed of the ball, which of the following will not change? • Speed • Velocity • Acceleration • Acceleration will not change, since gravity is a constant 9.8m/s2

  40. 30. When doing an experiment with small rolling toys, what would be the best lab safety equipment to wear? GOGGLES!!! (No, you won’t need gloves…)

  41. A 500 kg motorcycle is racing at 20m/s. It is bumped from behind for one second with a force of 5,000N. What is his new speed? (Pretend friction is negligible—no friction) • V1 = 20m/s • Speed after one second = ? • a = F/m • V2 = V1 + the bumped speed = ? • Since acceleration is in m/s2, and the time is only one second, then the new acceleration will actually just be in m/s, since it does not go more than one second.

  42. To find the speed after one second: • a=F/m = 5,000N/500kg • a = 10m/s2 • Since the cycle only accelerated for one second, the acceleration will not continue each second, so will be a one-time acceleration (speed, since it won’t continue) of 10m/s • Add the speed after being bumped to the original speed: • 20m/s + 10m/s = 30 m/s

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