Speed and Acceleration Lab Name:______
Problem: What factors and forces affect the speed and acceleration of a moving object?
Background Knowledge:
· Speed is the distance an object travels per unit of time. Speed can be expressed as kilometers per hour (km/hr), meters per second (m/s), and so on. In most cases, objects don’t travel at a constant speed. Therefore, the average speed is used to describe the motion.
s = speed, t = time, and d = distance
· Acceleration is the rate at which an object’s speed changes. Acceleration can be expressed as meters per second per second (m/s/s or m/s2). Forces such as gravity, air resistance, and friction can cause an object to decelerate (decrease speed over time). Other forces can cause and object to accelerate (increase speed over time). If the car does not encounter these forces and travels at a constant speed, then it is not changing speed and there is no acceleration or deceleration.
a = acceleration, v = change in velocity or speed, and t = time
v = final velocity or speed – initial velocity or speed
Hypothesis:
What will be the average speed of a cart rolling down a ramp and traveling 5m?
Will the cart continually accelerate as it travels the 5m? Or will it decelerate?
Experiment:
Materials- Masking tape, meter stick, ramp, classroom char, toy car, and stopwatch.
Procedure-
1. Chose an open space (5m) in the hallway. Set up your launching ramp using the classroom chair and the metal ramp.
2. Place a masking tape marker where the ramp touches the floor and label it 0m. Label also 1m, 2m, 3m, 4m, and 5m markers.
3. Take some practice runs with the cart. You may need to adjust the height of the ramp, your cart, or use a manila folder to smooth the transition from the ramp to the floor. You need the cart to go at least 5m.
4. Launch the cart from the top of the ramp and begin timing it at the 0m mark. Stop the timer at each marker. You will need to take enough trial runs to get 4 timing measurements for each of the following distances: 0m to 1m, 0m to 2m, 0m to 3m, 0m to 4m, and 0m to 5m. Record your times in the data table.
5. Calculate the average time for each meter marker and record in data table.
Data:
Trial / Time(s)1.0 meter / 2.0 meters / 3.0 meters / 4.0 meters / 5.0 meters
1
2
3
4
Average
Analysis:
Record your average time from table 2 for each below.
a. 0m to 1m ______
b. 0m to 2m ______
c. 0m to 3m ______
d. 0m to 4m ______
e. 0m to 5m ______
Calculate the instantaneous speed at the following distances
f. 1m ______(1/a)
g. 2m ______(2/b)
h. 3m ______(3/c)
i. 4m ______(4/d)
j. 5m ______(5/e)
Calculate the time between each of the following distances
k. 1m to 2m ______(b – a)
l. 2m to 3m ______(c- b)
m. 3m to 4m ______(d – c)
n. 4m to 5m ______(e – d)
Calculate the acceleration for the following distances
o. 1m to 3m ______(h – f/k + l)
p. 2m to 4m ______(i – g/l + m)
q. 3m to 5m ______(j - h/m + n)
Graph: Make a double-line graph showing the instantaneous speed (f through j) and the average speed for the whole run 0 – 5m (j); your average speed will be constant. Your x-axis should be distance and your y-axis should be speed.
Conclusion:
1. What force caused the car to move? ______
2. Describe the motion of the car as it moved across the floor. ______
3. What caused the car to slow down and/or stop? ______
4. Look at the graph you made. Compare the average speed to the instantaneous speed.______
5. When is it helpful/ appropriate in life to use average speed?______
6. When is it helpful/ appropriate in life to use instantaneous speed? ______
7. How could you increase the speed of the car? How could you decrease the speed? ______
8. Explain any instance in which the car accelerated? ______
9. Consider only the 5 meters the car traveled. What conditions are necessary for the moving car to have zero acceleration? ______