Question

• always use significant figure rules. remember that these rules apply to all numbers that are measurements.
• in working this problem, assume the value of g to be 9.8 m/s² with two (2) significant digits unless otherwise stated.

a force of 80 n is exerted on an object on a frictionless surface for a distance of 4 meters. if the object has a mass of 10 kg, calculate its velocity.
v = ______ m/s
○ 64
○ 8
○ 6
○ 32

Explanation:

Step1: Calcular el trabajo

El trabajo \(W\) se calcula como \(W = F\times d\). Dado \(F = 80\ N\) y \(d=4\ m\), entonces \(W=80\times4 = 320\ J\).

Step2: Relacionar trabajo y energía cinética

Según la ley del trabajo - energía, \(W=\Delta K\). Si el objeto parte del reposo (\(v_{0} = 0\)), entonces \(W = K=\frac{1}{2}mv^{2}\). Despejando \(v\), tenemos \(v=\sqrt{\frac{2W}{m}}\). Sustituyendo \(W = 320\ J\) y \(m = 10\ kg\), \(v=\sqrt{\frac{2\times320}{10}}=\sqrt{64}=8\ m/s\).

Answer:

B. 8