A 55 kg skater at rest on a frictionless rink throws a 3 kg ball, giving the ball a velocity of 8 m/s. What is the velocity of the skater immediately after?

Velocity's direction will be in opposite to direction of ball.

Explanation:

Momentum = 8m/s,

using law of conservation of momentum;

              50v + 20 = 0 (as initial momentum is zero)

or

p = m/v (m is mass and v is velocity)

v = p/m  (p is momentum)

putting values;

v = 20/50

  = 0.4 m/s

it proves that direction of velocity is opposite direction of ball.

electrical power

the temperature in kelvin of 2.0 dm3 of an ideal gas is doubled and its pressure is increased by a factor of four. what is the final volume of the gas