_{1}and m

_{2}respectively, released from the same height

**h**to the ground.

Under the condition: mass m

_{2}=2*m

_{1}

The time for object to reach the ground are T

_{1}and T

_{2}respectively,

Normally, the air reststance can be ignored for heavy objects, and we know that

T

_{2}=T

_{1}=, where g is the gravity.

If the impact forces are F

_{1}and F

_{2}respectively.

What is the relation between F

_{1}and F

_{2}?

A. F

_{2}>2*F

_{1}

B. F

_{2}=2*F

_{1}

C. F

_{2}<2*F

_{1}

The impact force F=△P/△T, where △P is the momentum change during the impact and △T is the impact time.

Both object drop from the same height, so the velocity when impact start is ,

So △P

_{2}=2*△P

_{1}.

We need to know the relation between △T

_{2}, △T

_{1}in order to compare F

_{2}/F

_{1}.

If △T

_{2}= △T

_{1}, then F

_{2}=2*F

_{1}.

However, is it true that △T

_{2}= △T

_{1}

If △T

_{2}> △T

_{1}, how to find out relation between F

_{1}and F

_{2}?

You can check out the answer with the following simulation:

The impact time △T and F

_{averege}will be shown. F(t) is available, too!

The impact force is modeled with .

**Press the Alt key and the left mouse button to drag the applet off the browser and onto the desktop.**This work is licensed under a Creative Commons Attribution 2.5 Taiwan License

- Please feel free to post your ideas about how to use the simulation for better teaching and learning.
- Post questions to be asked to help students to think, to explore.
- Upload worksheets as attached files to share with more users.