Worksheet 02 Kinematics I PDF

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Physics 1118 Worksheet 02: Kinematics I – Graphical representation of motion 1. Give an example of a situation where (a) the average speed equals the magnitude of the average velocity and (b) the average speed and the magnitude of the average velocity differ.

2. The initial ( t = 0 ; black silhouette) and final ( t = 8 s ; grey silhouette) positions of four people are shown on the right. If moving, the motion is at constant speed. Answer the following pertaining their motion. (a) From t = 0 to t = 8 s , the people’s displacements are: x1 = __________________________

x2 = __________________________ x3 = __________________________ x4 = __________________________ (b) Below, graph the position-vs-time graph for each person.

(c) For those moving at constant speed, how is this commonality reflected in the graphs above?

(d) According to the figures (not the graphs), which person is moving faster? ____________________ How is this fact reflected in the person’s position ( x ) vs time ( t ) graph – in comparison to the other?

(e) Answer the following for the graphs of persons 2 and 3: What do they have in common?

What difference is there?

(f) For person 4, describe the person’s state of motion and associated x -vs- t graph. Use precise language.

(g) Based on the above, an object that moves at constant speed has a position - vs- time graph that looks like ______________________________ (call this answer). If the object moves fast and to the right, the (answer) has these features:

If the object moves slow and to the left, the (answer) has these features:

By calculating the _______________ of an object’s position-vs-time graph, we obtain the object’s ___________________.

3. The velocity vs time graph shows the motion of a car. Answer the following questions as required. Assume that positive is to the right.

(a) Indicate the sign (+, - , 0) of the velocity, acceleration and displacement at the times or time intervals indicated.

(t1 , t2 ) (t2 , t3 ) (t3 , t4 ) (t 4, t 5 )

t3

t5

Velocity Acceleration Displacement (b) Indicate the time intervals when the speed is decreasing: _____________________ increasing: ______________________ constant: ___________ (c) Indicate the time(s) when the car is changing direction: _______________________ (d) If the car was initially on the right side of the origin (for some defined origin), on what side of the origin is it at t5 ? Justify your answer.

4. The graph shows the motion of a dog. In the interval 0 s to 10 s, what are the dog’s … (a) displacement?

(b) total distance traveled?

(c) acceleration(s)?

5. Do as indicated for each of the following graphs. Graph 1 (a) What is the speed of object B at t = 0? Explain.

(b) Do objects A and B ever have the same speed? If so, at what time or times? Explain.

Graph 2 The graph shows the position graph for an object moving along the x -axis. (a) Draw the corresponding velocity vs time graph in the space provided.

(b) At what time(s) is the acceleration positive?

Graph 3

Sketch the position vs time graph for an object – moving along the x-axis – that (i) starts from rest at the origin; (ii) has positive acceleration for the first 4 seconds; (iii) continues to move with the same velocity for the next 3 seconds; (iv) remains stationary for the rest of the time....