SUPPLEMENTAL PRACTICE PROBLEMS Chapter 9.5 SOLUTIONS

1) In the Antarctica, there is an ice sheet covering the Ross Sea. It has retreated 700 km in the past 7000 years. What has been the speed of this retreat? d = 700 km, t = 7000 a, Vav = ? Vav = Δd = 700 km Δ t 7000 a = km / a The velocity of the retreat is km / a

2) When chasing prey, walruses can travel at speeds of 30 km/h. If they spend 4 hours hunting, what distance will they travel? Δ d = ?, Vav = 30 km / h, Δ t = 240 min Δ d = Vav Δ t = (30 km /h ) ( 4.00 h) t = 240 min x 1 h = 4.00 h = 120 km 60 min = 1.2 x 10 2 km The walruse will travel 1.2 x 10 2 km at a velocity of 30 km/h.

3) An iceberg that breaks off a glacier will move at a speed of 1.5 km/h. If scientists found that one of these icebergs had traveled 6.0 km, how long did it take to travel this distance? Δ d = 6.0 km, Vav = 1.5 km/h, Δ t =? Δ t = Δ d = 6.0 km Vav 1.5 km /h = 4.0 h The iceberg took 4.0 hours to travel 6.0 km.

4) Kira wants to bike to the beach which is 45 km away. She can bike at an average speed of 20 km / h. How long will the trip take her? Δ d = 45 km, Vav = 20 km/h, Δ t =? Δ t = Δ d = 45 km Vav 20 km /h = 2.3 h = 2 h Kira will take about 2 h to travel 45 km.

5) Jana works with buffalo. She notes that they graze at an average speed of 110 m/h for about 7.0 hours each day. How many kilometres will the herd travel in two weeks? Per day: Δ d = ?, Vav = 110 m / m/h, Δ t = 7 h / day Δ d = Vav Δ t = 110 m / h ( 7 h) = 770 m For two weeks: 770 m x 14 days = m Convert to km m = km 11 km (Significant digits) The herd will travel approximately 11 km in two weeks.

6) Average speed is the total distance divided by the total time whereas instantaneous speed is the speed at a particular instant in time. 7a) The car will go a further distance than the truck in the same length of time. 7b) The car would take less time than the truck traveling the same distance. 8a) 5.2 km / h 8b) 14 km / h 8c) 7.6 km 8d) 78 h

9) The cruise control of a car is set at 90 km / h. What distance is traveled by the car during 2.50 h? Note: You do not need the delta (triangles) as the speed is not average. Note: You do not need the delta (triangles) as the speed is not average. d = ?, v = 90 km / h, t = 2.5 hd = vt = 90 km / h ( 2.5 h) = 225 km The distance traveled is 225 km.

10) The Breitling Orbiter 3 balloon set world records in 1999 by traveling km in 19 days, 21 hours and 47 minutes. On March 1, 1999, the balloon lifted off from a village in the Swiss Alps. It eventually landed in Egypt on March 21. a) Calculate the average speed of the balloon. Δd = km, Vav = ? t = 19 days, 21 hours, 47 minutes - Convert to hours 19 days x 24 = 456 hours 21 hours 47 min / 60 min = 0.78 hour hours Vav = Δd = km Δ t h = km / h The average speed is km / h.

10 b) What length of time did it take the Breitling Orbiter 3 to cross the Atlantic Ocean, a distance of 6670 km? Δd = 6670 km, Vav = km / h, Δ t = ? Δ t = Δ d = 6670 km Vav km /h = h = 78.1 h The average time is 78.1 h.

10 c) In the final leg of the round – the –world trip, the balloon flew for 18 h at an average speed of 210 km / h. How far did it travel? Δd = ?, V av = 210 km / h, Δ t = 18 h Δd = V av Δt = 210 km/h x 18 h = 3780 km The distance traveled was 3780 km.