Chapter1, Lesson B - Mass, Weight and Gravitational Acceleration: Keebos and Tweeks

1B-9 :	Mass, Weight and Gravitational Acceleration: Keebos and Tweeks							5 pts

In an alien system of units, the unit of mass is a Keebo and the unit of force is a Tweek. One Tweek is the weight of a mass of one Keebo on the Mercury. The average gravitational acceleration on Mercury is 3.59 m/s2.
a.)	What is gc in this system ? Be sure to include the numerical value and the units.
b.)	How much would a 700 Keebo person weigh on the surface of Mercury, in Tweeks ?
c.)	How much would a 700 Keebo person weigh on the surface of the Earth, in Tweeks ?
d.)	To which system of units is the Keebo-Tweek system most similar, SI or AE ?

Read :	1 Keebo exerts 1 Tweek of force when a = 3.59 m/s2.
	The key here is that Newton's 2nd Law of motion applies regardless of where the system is located or what system of units is used.


Given :	amoon	3.59	m/s2
	m	700	Keebo

Solution :	Newton's 2nd Law :							Eqn 1

Part a.)	Solve Newton's 2nd Law for gc :							Eqn 2

Answers :				gc	3.59	m-Keebo/Tweek-s2

Part b.)	Solve Newton's 2nd Law for F :							Eqn 3


Answers :				F	700	Tweek


Part c.)	The acceleration of gravity at the surface of the Earth is:					aEarth	9.8066	m/s2

	Solve Newton's 2nd Law for F :							Eqn 4


Answers :				F	1912	Tweek


	There are two important points to this problem:
	1 - The value of gc is the same everywhere in the universe.
	2 - If a person weighs a certain amount more on the Earth than on Mercury in one system of units, then he or she also weighs proportionally more on the Earth than on Mercury in any other sytem of units as well !


Part d.)	The Keebo-Tweek system of units is analogous to the American Engineering System of units because gc is not equal to 1 and 1 unit of mass exerts 1 unit of force (on Mercury).
Answers :

Example Problem with Complete Solution