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Microgravity: living on the International Space Station
Microgravity: living on the International Space Station

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2 Using drop towers to simulate microgravity

When objects are dropped from the top of drop towers, they achieve freefall as they drop. This briefly creates a microgravity environment (Figure 4).

A coloured photograph of the Bremen drop tower.
Figure 4 The 140-metre drop tower in Bremen, Germany.

Listen to Audio 1 which describes drop towers and rollercoasters. A transcript is also provided if you would prefer to read it.

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Audio 1 drop towers and rollercoasters
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According to this New Scientist article [Tip: hold Ctrl and click a link to open it in a new tab. (Hide tip)] (Cross, 1990), up to 10 seconds of a microgravity environment can be replicated in the Japan Microgravity Centre (JAMIC) (Figure 5).

Described image
Figure 5 The Japan Microgravity Centre or JAMIC (Cross, 1990).

To test your understanding of freefall and drop towers you should now complete Activity 2.

Activity 2 Drop towers and freefall

Timing: Allow approximately 15 minutes

Choose the correct answers to the following questions.

1. The Bremen drop tower is 140 metres high and objects freefalls from top to bottom in 4.6 seconds. What is the average speed achieved by objects in this drop tower? (Hint: divide distance by time. Then round your final answer to 2 significant figures.)

a. 

3.0 m/s


b. 

300 m/s


c. 

30 m/s


d. 

0.30 m/s


e. 

3000 m/s


The correct answer is c.

Answer

Actually, because it just gets faster and faster, thinking of this as an average speed is not particularly helpful.

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3. JAMIC’s 700-metre drop tower provides a 500-metre freefall distance in about 10 seconds. What is the average speed of an item when dropped into the JAMIC? (Hint: divide distance by time.)

a. 

500 m/s


b. 

7 m/s


c. 

5 m/s


d. 

50 m/s


e. 

70 m/s


The correct answer is d.

4. As Felix Baumgartner achieved about 370 m/s during his freefall, he was about ___ times faster in freefall than the average speed achieved by an item dropped in the Bremen drop tower (Question 1).

(Hint: divide Felix’s rounded speed by the rounded speed achieved in the drop tower. Then round your answer to 2 significant figures.)

a. 

12


b. 

120


c. 

1.2


d. 

0.12


e. 

0


The correct answer is a.

Next, you will carry out your own experiment to calculate the acceleration of gravity on Earth.