TUTO 1 B

TUTORIAL 1B-PHYSICS, SHF 1215, SEM 2, 2010/2011

1 A whale swims due east for a distance of 6.9 km, turns around and goes due west for 1.8 km, and finally turns around again and heads 3.7 km due east (east as positive direction).
a) What is the total distance traveled by the whale?
b) What are the magnitude and direction of the displacement of the whale?

2 A student stays 6.0 km from the main road. His school is 12 km from the junction P as shown in figure below.

He takes 10 minutes to travel from his house to junction P, and another 15 minutes from the junction to his school which is 12 km from the junction P as shown. Assume that the student travels with constant speed from the house to the junction P and from the junction P to the school. Calculate the student’s
i. Average speed from his house to the school (ans: 0.72 km/min or 43.2 km/hr)
ii. Average velocity from his house to the school (ans: 32.3km/h)
iii. The change of velocity at the junction


3 Complete the graphs below, by drawing in the missing graphs, where each row represents identical motion:

4 Figure 1 shows the distance of a car along a straight path as a function of time.


i. What is the average speed of the object from time = 0 s to time = 5 s?

ii. What is the instantaneous velocity of the object at time = 16s?
5 The following velocity-time graph represents the movement of a car that was initially travelling towards the East.


(a) At which stage(s) did the car have a constant velocity?
(b) Use the graph to calculate the acceleration from E to F.
(c) Use the graph to determine the displacement of the car between A and C.
(d) Describe the motion of the car from B to C.
6 a. A cyclist accelerates at 0.89 m/s2 during a 5.00 second interval. What is the change in velocity of the cyclist?

b. Starting from rest, a light plane must reach a speed of 30.0 m/s for takeoff. How long a runway is needed if the acceleration is 3.0 m/s2?

c. A uniformly accelerating train passes a green light signal at 7.00 m/s. It passes a second light 125 m farther down the rail track, 12.0 s later. Determine the acceleration of the train.

d. A car traveling 24 m/s on a straight road is brought uniformly to a stop in 10 s. How far does the car travel during that time?

7 A truck on a straight road starts from rest and accelerates at 2.0 m/s2 until it reaches a speed of 20 m/s. Then the truck travels for 20 s at constant speed until the brakes is applied, stopping the truck in a uniform manner in an additional 5.0s.
a. How long was the truck in motion? (ans: 35 s)
b. What is the average velocity of the truck for the motion described? (ans: 15.7m/s)

8 A zebra first sees a lion when the lion is 12.5 m away and moving towards the zebra with a velocity of 5 ms-1. The zebra begins to accelerate away from the lion; at the same time the lion accelerates towards the zebra at 2 ms-2.

(a) If the lion takes 15 seconds to catch the zebra, how far does the zebra travel before it is caught? (4)

(b) What is the zebra’s acceleration, if it’s moving at 38 ms-1 when the lion catches it?

9 An SUV blows through a red light at a constant velocity of 42.5 m/s. At the same instant, a police car at the same red light floors the gas pedal and accelerates at 4.2 m/s2 after the SUV.

a) How long does it take for the police car to overtake the SUV?
b) How far down the road are they when the police car catches up?
c) How fast is the police car going when he catches up to the SUV?
10 A girl throws a ball from the edge of a balcony which is 15.0 m above the ground. She throws it with a velocity of 12.5 m/s vertically upwards and the ball reaches a height of 8.0 m above the balcony, then it falls straight down to the ground.
(a) What is the displacement from where of the ball at maximum height?

(b) What is the displacement of the ball when it on the ground?
(c) What distance does the ball travel?
(d) What is the acceleration of the ball when at maximum height?
(e) What is the acceleration of the ball as it passes the balcony on the way down.
(f) Calculate the final velocity of the ball just as it hits the ground.

11 Zipho throws a ball vertically upward with an initial speed of 15.0 ms-1 to Ntombi who is leaning over a balcony that is 8.0 m above Zipho’s hand. She catches the ball on its way down. Calculate:
a. The velocity of the ball when she catches it.
b. The time taken to reach Ntombi.