Weight = (mass) x (gravity)
70 N = (mass) x (9.8 m/s²)
Divide each side by (9.8 m/s²) , and you have
mass = 70 N / 9.8 m/s² = 7.14 kg.
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Mass on the moon:
Mass doesn't change. It's a number that belongs to the bowling ball,
no matter where the ball goes. If the mass of the bowling ball is 7.14 kg
anywhere, then it's 7.14 kg everywhere ... on Earth, on the moon, on Mars, rolling around in the trunk of my car, or floating in intergalactic space.
However, WEIGHT depends on the gravity wherever the ball happens to be
at the moment.
The acceleration of gravity on the moon is 1.622 m/s².
So the WEIGHT of the ball on the moon is
(7.14 kg) x (1.622 m/s²) = 11.58 Newtons
That's only about 16% of its weight on Earth.
The water in a reservoir behind a hydropower dam is another example of potential energy. The stored energy in the reservoir is converted into kinetic energy (motion) as the water flows down a large pipe called a penstock and spins a turbine.
None of these are a good definition; a good definition would be "the maximum velocity that an object can fall at." however the best answer out go those is c. the constant velocity of some falling objects.
We can solve the problem by using conservation of momentum.
The player + ball system is an isolated system (there is no net force on it), therefore the total momentum must be conserved. Assuming the player is initially at rest with the ball, the total initial momentum is zero:
The total final momentum is:
where 
is the momentum of the player and 
is the momentum of the ball.
The momentum of the ball is: 
While the momentum of the player is: 
, where M=59 kg is the player's mass and vp is his velocity. Since momentum must be conserved,
so we can write
and we find
and the negative sign means that it is in the opposite direction of the ball.
