Question

forces that change motion quick check
recall that the formula for momentum is:
$$ p = mv $$
which of the following correctly shows momentum being calculated?
(1 point)
$$ 45 kg * m/s = (9 kg)(5 m/s) $$
$$ 4 kg * m/s = (9 kg)(5 m/s) $$
$$ 45 n = (9 kg)(5 m/s) $$
$$ 14 kg * /s = (9 kg)(5 m/s)s $$

Explanation:

Step1: Calculate the right - hand side of each option

For the formula \(P = mv\), when \(m = 9\space kg\) and \(v=5\space m/s\), we calculate \(mv\).

$$mv=(9\space kg)\times(5\space m/s)$$

$$mv = 45\space kg\cdot m/s$$

Step2: Check the units and values of each option

• Option 1: \(45\space kg\cdot m/s=(9\space kg)(5\space m/s)\). The value of \((9\times5) = 45\) and the unit of momentum \(P\) is \(kg\cdot m/s\).
• Option 2: \((9\space kg)(5\space m/s)=45\space kg\cdot m/s

eq4\space kg\cdot m/s\)

• Option 3: The unit of \(P\) is \(kg\cdot m/s\), not \(N\) (Newton is the unit of force \(F = ma\), where \(a\) is acceleration in \(m/s^{2}\))
• Option 4: \((9\space kg)(5\space m/s)s = 45\space kg\cdot m

eq14\space kg\cdot/s\)

Answer:

\(45\space kg\cdot m/s=(9\space kg)(5\space m/s)\)