Motion Review Answers June 2009 Wiki

Motion Review Final Exam June 2009

1.

You are taking a trip from Oshawa to Niagara Falls in your family car. The total distance from Oshawa to Niagara Falls is 170 km. In the pursuit of science, you decide to measure certain physical quantities. The odometer on the car reads 28 456.0 km at the beginning of the time interval measured, and at the end of the time interval of 1.35 hours it reads 28 577.5 km

(d)Determine the average speed of the car during this time period in kilometers per hour. (g)Assuming this average speed will be maintained, how long will it take to travel to Niagara Falls from Oshawa in hours?

1.

You are taking a trip from Oshawa to Niagara Falls in your family car. The total distance from Oshawa to Niagara Falls is 170 km. In the pursuit of science, you decide to measure certain physical quantities. The odometer on the car reads 28 456.0 km at the beginning of the time interval measured, and at the end of the time interval of 1.35 hours it reads 28 577.5 km

(a) Determine the average speed of the car during this time period in kilometers per hour.. (a) ∆d = 28 577.5 km – 28 456.0 km = 121.5 km ∆t = 1.35 h Vav = ? km/h Vav = ∆d ∆t = 121.5 km 1.35 h = 90.0 km/h (3 significant digits) The average speed of the car is 90.0 km/h.

1.

You are taking a trip from Oshawa to Niagara Falls in your family car. The total distance from Oshawa to Niagara Falls is 170 km. In the pursuit of science, you decide to measure certain physical quantities. The odometer on the car reads 28 456.0 km at the beginning of the time interval measured, and at the end of the time interval of 1.35 hours it reads 28 577.5 km

(b) Assuming this average speed will be maintained, how long will it take to travel to Niagara Falls from Oshawa in hours? (b)

∆t = ∆d Vav = 170 km 90.0 km/h = 1.89 h (rounded to 3 significant digits) The family will make the trip from Oshawa to Niagara Falls in 1.89 hours.

•

It has been proven that one-quarter of all vehicle accidents occur because the driver is distracted. “Drive Thru’” dining is a convenience we take for granted in our modern society. Assume that a driver was eating french fries while driving and dropped one of the french fries on the seat. He looks down, sees the fry, and reaches to pick it up. It takes him approximately 3.0 s to look and pick up the french fry.

How far in metres does the car travel in this time if he is travelling at a constant speed of 100 km/h? v = 100 km/h ∆t = 3.0 s x 1 min x 1h = 0.000 83 h 60 s 60 min ∆d = ? ∆d = v ∆t = 100 km/h x 0.000 83 h = 0.083 km 0.083 km x 1000 m = 83 m 1 km

The car travelled 83 metres in the 3.0 seconds it took the driver to recover the french fry.

3. A baseball is thrown by a pitcher at a speed of 144 km/h and comes to rest in the catcher’s glove. The acceleration of the ball is –150 000.0 km/h2. What time in seconds does it take to get from the pitcher to the catcher?

v1 = 144 km/h v2 = 0.00 km/h Aav= 150 000.0 km/h2 ∆t = ? ∆t = v2 - v1 Aav = (0.00 – 144) km/h -150 000.0 km/h2 = 0.000 960 h (rounded to 3 significant digits) ∆t = 0.000 960 h x 60 min x 60 s = 3.46 s 1h 1 min It took 3.46 s for the ball to accelerate from 144 m/s to 0.00 m/s.

4. A car accelerates at 8.1 (km/h)/s. How long in seconds would it take to accelerate from 20.0 km/h to 50.0 km/h? v1 = 20.0 km/h v2 = 50.0 km/h Aav= 8.1 (km/h)/s ∆t = ? ∆t = v2 - v1 Aav = (50.0 – 20.0) km/h 8.1 (km/h)/s = 3.7 s

It will take 3.7 s for the car to accelerate from 20.0 km/h to 50.0 km/h.

Distance-time Graph Problems 1) On a bicycle trip a student records the distance from home every hour. The following data was collected: Time (hours)

Distance (km)

1

9.5

2

20.0

3

30.0

4

40.5

5

50.0

6

59.5

1.

Plot the graph.

(Axis values? Axis scales? Axis labels and units?)

1. a) Find the slope of the graph’s best fit line. (Make a smooth line, not point-to-point)

b) What does the slope tell us about the motion of the bicycles? (Slope units?)

3. What data set (Time or Distance) is the independent variable? The dependent variable?

1. How many hours does it take to cover 35 km?

5. How far from home would the student be after 7 hours?