Day One Review Sheets

Day One Review Sheet: Velocity, acceleration, distance, braking distance, stopping distance, reaction time

1. Equations:

d = vt t = d/v

2. Typical reaction time is 0.3sec or 1/3 sec

3. Definitions

Symbol Name Concept d Distance v velocity Change in distance over time t time a acceleration Change in velocity over time Reaction time Typical time to react to an event (0.3sec) Braking distance Distance to stop once brakes are applied Braking Time Time to stop once brakes are applied Stopping time Time to stop once an event occurs. SUM OF BRAKING TIME PLUS REACTION TIME Stopping distance Distance to stop once an event occurs. SUM OF BRAKING DISTANCE PLUS REACTION DISTANCE

4. Kayla drives 10 miles at 20 miles per hour. For how long does she drive?__10/20 = 0.5______

______

5. Rebecca drives for 10.5 hours at 35 miles per hour. How far does she drive?______

____10.5 * 35 = 367.5______

6. Fabrizio rides his bicycle for a distance of twenty-seven miles. He takes 14 hours to do so. What

speed does he ride at?___27/14 = 1.93______

Concept 1: The slope of a graph of distance versus time gives me the __velocity___.

Concept 2: __Acceleration______is the change in velocity over time.

Concept 3: The slope of a graph of velocity versus time gives me the __acceleration______.

7. John takes a very long walk.

a. How far does he go in 8 hours?___16km______

b. What speed is he going at?______2km/hr______

c. Is he accelerating?______No______8. Nick takes a long bicycle ride.

a. What is the distance traveled after six hours?__50km______

b. What is his speed after six hours?______12km/hr______

c. Is Nick accelerating?______Yes______d. How can you tell if Nick is accelerating?______Speed is increasing______

9. One mile = 1.61 km, or 0.62 miles = 1 km

a. If I drive 10 miles, how many km have I driven?_____16.1km______

b. If I drive 5km, how many miles have I driven?______3mi______

c. If I drive 5 miles, how many km have I driven? How many meters?

c.i. ______8km______

c.ii. ______8000m______Concept 4: Response time is the time it takes for a person to respond to a stimulus (something that happens). It is independent of the speed at which you are traveling. The older you are, the slower you tend to be at responding. Reaction time (response time) is affected by many things, including time of day, drugs and alcohol, amount of sleep, the presence of friends, cell phones, texting, etc. Be prepared to list at least three of these or similar distractions.

10. What is a typical reaction time?______0.3sec or 1/3 sec______

11. If I am going at 10m/sec and Leah runs out in front of my car, how far do I go before I can hit the

brakes?______3m______

12. The braking distance goes up with the square of the velocity. (This is because the braking

distance increases as the kinetic energy increases)

13. Table of velocities and distances: Fill in the missing values

Speed (mph) Speed (f/s) Response time Braking distance Stopping Distance distance (f) (f) (f) 10 15 5 5 10 15 22.5 7.5 11.25 18 20 30 10 20 30 30 45 15 45 60 40 60 20 80 100 60 90 30 180 210

14. If I double my speed, how does that affect my reaction time?______No______

______

15. If I double my speed, how does that affect the distance I travel during my reaction time?

______2x______

16. If I double my speed, how does that affect my braking distance, that is, the distance I travel

while I am braking?______4x______

17. List three things that can affect my reaction time. __Drugs, cell phone, friends______

______

18. How does reaction time typically vary with age?

______increases______

19. I am traveling at 45mph and a child steps in from of my car at a distance of 150 feet. Will I be

able to stop in time? ____45mph = 67.5 ft/sec. So reaction distance is 20.25ft. Braking distance

is (67.5/60)^2*80 = 101.25. So stopping distance is 121.5. Child is safe.______20. What factors will affect the stopping distance of a car? (List 3)__Reaction time, brakes, road

condition, tires, weather.______