Question

Mr. Mann's science students were experimenting with speed. They set up a 1 meter (100 cm) track. The students used balls instead of cars. The balls were different sizes and made of different materials. Four at a time, students rolled balls around the track to see which had the fastest and slowest speeds.

BALL SPEED
Ball

Distance Traveled
(cm) Time Taken to Cover the
Distance (seconds)
Ball 1 100 10
Ball 2 50 20
Ball 3 100 20
Ball 4 50 10

Some of their data are shown in the table. Which ball will take the longest to complete one lap around the track?
Responses
A Ball 1Ball 1
B Ball 2Ball 2
C Ball 3Ball 3
D Ball 4

Answer 1

To determine which ball will take the longest to complete one lap around the track, we need to calculate the speed of each ball using the formula:

\[
\text{Speed} = \frac{\text{Distance}}{\text{Time}}
\]

Now we'll calculate the speed for each ball:

1. **Ball 1:**
- Distance = 100 cm
- Time = 10 seconds
- Speed = \( \frac{100 \text{ cm}}{10 \text{ s}} = 10 \text{ cm/s} \)

2. **Ball 2:**
- Distance = 50 cm
- Time = 20 seconds
- Speed = \( \frac{50 \text{ cm}}{20 \text{ s}} = 2.5 \text{ cm/s} \)

3. **Ball 3:**
- Distance = 100 cm
- Time = 20 seconds
- Speed = \( \frac{100 \text{ cm}}{20 \text{ s}} = 5 \text{ cm/s} \)

4. **Ball 4:**
- Distance = 50 cm
- Time = 10 seconds
- Speed = \( \frac{50 \text{ cm}}{10 \text{ s}} = 5 \text{ cm/s} \)

Now, to find out how long it takes each ball to complete one lap (100 cm), we can use the speed values we just calculated.

- **Time for Ball 1:**
\[
\text{Time} = \frac{100 \text{ cm}}{10 \text{ cm/s}} = 10 \text{ seconds}
\]

- **Time for Ball 2:**
\[
\text{Time} = \frac{100 \text{ cm}}{2.5 \text{ cm/s}} = 40 \text{ seconds}
\]

- **Time for Ball 3:**
\[
\text{Time} = \frac{100 \text{ cm}}{5 \text{ cm/s}} = 20 \text{ seconds}
\]

- **Time for Ball 4:**
\[
\text{Time} = \frac{100 \text{ cm}}{5 \text{ cm/s}} = 20 \text{ seconds}
\]

From these calculations, we can see that:

- Ball 1 takes 10 seconds.
- Ball 2 takes 40 seconds.
- Ball 3 takes 20 seconds.
- Ball 4 takes 20 seconds.

The ball that takes the longest to complete one lap around the track is **Ball 2**, taking 40 seconds.

Thus, the answer is:

**B. Ball 2**