### concept reinforcement quiz 1

Kinematics #### DEFINITIONS (often a formula will do!)

1. Define speed:

2. Define acceleration:

3. What does Δ mean in physics?

#### DESCRIPTIONS

• Why can't instantaneous speed be MEASURED?

• If you were in an elevator with no way to look out, which kind(s) of motion could you feel or detect?

• Describe how you might measure the speed of a car driving by using the least amount of complicated equipment.

#### PROBLEMS

For problems, the ANSWERS are NOT IMPORTANT!  But it is very useful to develop the ability to use known information to calculate or predict other valuable information.  For such problems you need to identify which formula or mathematical equation to use.  Note what information is given and what information is sought.  Try to find a formula that relates the given with the unknown desired information.
1. Once you have found a useful formula, write down the formula;
2. show the substitution of given (or common) information into the formula;
3. solved the equation in steps, one step on each line; (e.g., isolate the unknown on one side of the equation.  This stepwise procedure has many benefits including helping to find any inadvertent errors.)
4. finally give the answer to the correct number of significant figures, and with appropriate units labelled.
If you believe you need more information to solve the problem, such as the number of seconds in an hour, specify additional assumptions that you believe are necessary.
• A car was timed consuming 10.0 s to transverse a quarter mile from a standing start.  What was its average speed in miles per hour?

• If the car above started from rest, and it averaged the speed above, what was the final speed at the end of the quarter mile?

• A tsunami travels at 790 km/hr, how long would it take for the wave to arrive 2200 km away?

• An airplane might accelerate from rest to a take off speed of 160 km/hr in 15 s.  What is the average acceleration of the airplane?

Essays, graphs and equations are common methods for communicating about physics. But there are other effective methods too.

• Graph the displacement, speed, and acceleration verses time for a object shown in a strobe photograph:

• Describe the motions shown in by strobe photograph:

• Describe the motions shown in by a displacement, speed, and acceleration verses time graph:

• Write a poem describing an object accelerating:

• Create a cartoon about acceleration:  