For each problem: The known values
What value you are trying to solve for
The formula needed
Substitute the known values into the formula and solve.
4. A girl does 27 J of work to lift a moving box 0.6 m. How much does the box weigh?

5.You serve a volleyball with a mass of 2.1 kg. The ball leaves your hand with a speed of 25 m/s. What kind of energy does the ball have? Now Calculate it (show your work).

6.A baby carriage is sitting at the top of a hill that is 32 m high. The carriage with the baby has a mass of 15 kg. What kind of energy does the carriage have? Calculate it?

the answer to this question is 3.

(newtons first law)

conservation of momentum law states :

momentum before collision = momentum after collision

momentum p (kg-m/s)= mass * velocity

say moving car=1 000 kg, velocity = 10 m/s then p = 1 000*10= 10 000 kg-m/s

say still car = 2 000 kg, velocity = 0 m/s then p = 2 000* 0 = 0 kg-m/s

total momentum prior to collision = 10 000 + 0 = 10 000 kg-m/s

momentum after collision = 10 000 kg-m/s

mass now = 1 000 kg+2 000 kg = 3 000 kg

10 000 = 3 000 kg* velocity m/s

10 000/3 000 = velocity

3.33 m/s = velocity after collision

an impulse is a force applied over time , momentum is exclusive of external forces and a perfect collision is implied