Kopnięta poziomo piłka o masie 1,5 kg 1,5 kg w momencie kopnięcia uzyskała przyspieszenie 5 m s 2 5ms2 . Oblicz wartość siły kopnięcia. Po nasiąknięciu wodą masa piłki wzrosła do 2 kg 2 kg . O ile większej siły musi użyć zawodnik, aby nadać jej takie samo przyspieszenie jak poprzednio?

1) 7.5 N

2) 10 N

Explanation:

1)

We can solve this first part of the problem by using Newton's second law of motion, which states that the net force on an object is equal to the product between its mass and its acceleration:

where

F is the net force

m is the mass of the object

a is its acceleration

In this problem we have:

m = 1.5 kg is the mass of the ball

is the acceleration

So, the kick force on it was:

2)

In this case, the mass of the ball has increased to

m' = 2 kg

We can also solve this part by using again Newton's second law of motion:

where

F' is the new kick force

m' = 2 kg is the new mass of the ball

a is the acceleration

The acceleration is the same as before,

Therefore, the new kick force is:

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v=ir = 3x15 =45 v