PENNY FINGERS

6 grams (600 milligrams) is subtle but not beyond a set of well-tuned senses. If one penny on each finger is below your threshold, try two pre-1982s stacked on one finger and two post-ig82S stacked on the other. Share this activity with a friend 

Was this your answer Yes, absolutely The moon exerts a downward gravitational pull on any body near its surface, as evidenced by the fact that astronauts were able to land and walk on the moon. This NASA photograph shows an astronaut jumping. Without gravity, this jump would have been his last. 

since there is gravity, why doesn t the flag droop downward Look carefully and you ll see that it is held up by a stick across its top edge. There is no wind on the moon (because there is no atmosphere), and so the crew used the support stick to make the wrinkled flag display nicely in photographs. 

This activity challenges any misconceptions you might have about what determines volume as it answers the question Can one object have a greater mass than another and yet have the same vol-ume Try this activity and find out. 

narrow glass masking tape empty film canister with lid bunch of pennies 

At the end of each chapter, you will find follow-up discussions, called Insights, for each Hands-On Chemistry activity. Ideally, you should look over the Insights only after you have attempted the activity. The job of the Insights is to correct any misconceptions you may 

Pennies dated 1982 or earlier are nearly pure copper, each having a mass of about 3.5 grams. Pennies dated after 1982 are made of copper-coated zinc, each having a mass of about 2.9 grams. Hold a pre-1982 penny on the tip of your right index finger and a post-1982 penny on the tip of your left index finger. Move your forearms up and down to feel the difference in inertia—the difference of 

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You have to be moving the pennies up and down in order to optimize your threshold of detection. What you are sensing here is the difference in inertia. Recall that inertia is an object s resistance to any change in its motion. If you minimize the motion, you minimize your ability to detect any difference in inertia the two coins may have. Switch pennies between your left and right index fingers (with your eyes closed) to confirm your ability to detect a difference. 

With or without the motion, the pennies exert a downward pressure that your nerve endings sense. To feel this pressure, repeat the experiment with the pre-1982s on one index finger and the post-1982s on the other index finger, but this time keep your hands still. How many do you need to stack before you can sense a difference in pressure If you did this pressure experiment on the moon, would you need to stack more or fewer Why ... 

In rough terms, a penny sitting on the tip of your finger exerts a pressure of about 250 Pa. 

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