Two friends of different masses are on the playground. they are playing on the seesaw and are able to balance it even though their masses are different.

how are they able to balance on the seesaw?

1) they are able to balance torques due to gravity.
2) they are able to balance their respective energies.
3) all of these.
4) their densities are the same.
5) they are able to balance forces due to gravity.
6) they are able to balance their respective momenta.

In a vernier instrument the main scale is in 1/2 mm divisions .vernier is made by redividing 19 such divisions into 20 equal parts. calculate the least count of the instrument.

Determine the age of a fossil if it had only one eighth of its original carbon-14 content remaining?

Scientist have use computer models to create a series of maps that show how susceptible coastal cities in island countries are to the sea rising at different levels.the map shows that a 1 meter rise would swap cities all along the us eastern seaboard. a 6-meter sea level rise with sub merge a large part of florida. thermal expansion has already raise the oceans 10 to 20 centimeters the most likely cause,directly and indirectly, for such a rise in sea level is