Exemplo de Physics, 8.1 Linear Momentum, Force, and Impulse

Calculating Momentum: A Football Player and a Football

Problema e solução em inglês, como no livro original.

(a) Calculate the momentum of a 110 kg football player running at 8 m/s. (b) Compare the player’s momentum with the momentum of a 0.410 kg football thrown hard at a speed of 25 m/s.

Resolva no papel primeiro. Depois abra a solução um passo de cada vez e pare assim que conseguir terminar sozinho.

Estratégia
No information is given about the direction of the football player or the football, so we can calculate only the magnitude of the momentum, p. (A symbol in italics represents magnitude.) In both parts of this example, the magnitude of momentum can be calculated directly from the definition of momentum:

$p = m v$
Solução
Solution for (a)

To find the player’s momentum, substitute the known values for the player’s mass and speed into the equation.

$p_{player} = (110 kg) (8 m/s) = 880 k g \cdot m / s$
Solução
Solution for (b)

To find the ball’s momentum, substitute the known values for the ball’s mass and speed into the equation.

$p_{ball} = (0.410 kg) (25 m/s) = 10.25 k g \cdot m/s$
The ratio of the player’s momentum to the ball’s momentum is

$\frac{p_{player}}{p_{ball}} = \frac{880}{10.3} = 85.9 .$

0 de 3 passos abertos

Como foi?

Estratégia

Solução

Solução

Estratégia

Solução

Solução