An object is dropped near the earth's surface. At the end of 4.0 s, how fast is it falling in m/s? (Ignore air resistance.)

Question

egenriether · Answer

what have you tried so far?

anonymous · Answer

Nothing. I have no idea what to do or what formula to use. I'm not good at Physics & I can't memorize formulas. So I really have no idea where to start..

egenriether · Answer

The acceleration of earth (and all bodies) is constant.  Its units are meters per second per second or m/(s^2)  This gives you the velocity after some time.  For example if the gravitational acceleration of a planet is 10m/s^2 then after 1 second the object is falling 10m/s.  After 5 seconds it would be falling 50m/s, because the gravitational field is an acceleration field.  Use the gravitational acceleration of earth and multiply by the time it has been falling.

anonymous · Answer

It's been falling for 4 seconds, so 10*4 = 40 m/s or m/s^2 ? & Thank you for helping !

egenriether · Answer

NO! the rate of acceleration on earth is NOT 10!  that was an example.  look in your physics book.  its given by the variable lowercase "g".  Hint: it is close to 10.