Question

always use significant figure rules. remember that these rules apply to all numbers that are measurements.
if a boy (m = 50kg) at rest on skates is pushed by another boy who exerts a force of 200 n on him and if the first boys final velocity is 8 m/s, what was the contact time?
δt= s
32
20
2

Explanation:

Step1: Aplicar la ley del impulso

El impulso \( J = F\Delta t\) y también \(J=\Delta p = m(v_f - v_i)\). Dado que \(v_i = 0\) (el niño está en reposo inicialmente), entonces \(F\Delta t=mv_f\).

Step2: Despejar \(\Delta t\)

Despejando \(\Delta t\) de la ecuación \(F\Delta t = mv_f\), obtenemos \(\Delta t=\frac{mv_f}{F}\).
Sustituyendo \(m = 50\space kg\), \(v_f=8\space m/s\) y \(F = 200\space N\):

$$ \Delta t=\frac{50\times8}{200} $$

$$ \Delta t=\frac{400}{200}=2\space s $$

Answer:

\(2\space s\)