Homework Help: physics

Posted by y912f on Monday, February 16, 2009 at 8:35pm.

please check my answers

what are the SI units for momentum?

kg*m/s

which of the following is not involved in hitting a tennis ball?

a. kinetic energy
b. chemical potential energy
c. gravitational potential energy
d. elastic potential energy

i picked B

How much power is required to lift a 2.0 kg mass at a speed of 2.0 m/s?

4.0 J?

i'm not sure about the last one..thanks for checking:)

physics - Damon, Monday, February 16, 2009 at 8:38pm
How much power is required to lift a 2.0 kg mass at a speed of 2.0 m/s?

4.0 J?
-----------------------
NO
force = 9.81 * 2 Newtons
so power = 9.81*4 Newton meters/sec or Watts
physics - drwls, Monday, February 16, 2009 at 8:41pm
The first two are correct. For the last one, you have to multiply M g by vertical speed to get power in Watts (Joules per second).
2.0 x 9.8 x 2.0 = ? W

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