# An object with a mass of 4 kg is hanging from a spring with a constant of 2 (kg)/s^2. If the spring is stretched by 5 m, what is the net force on the object?

Jan 2, 2018

The net force is $= 29.2 N \text{downwards}$

#### Explanation:

Solving in the downward direction ${\downarrow}_{+}$

The acceleration due to gravity is $g = 9.8 m {s}^{-} 2$

The weight of the object is $\vec{w} = m g = 4 \cdot 9.8 = 39.2 N$

The spring constant is $k = 2 k g {s}^{-} 2$

The extension is $x = 5 m$

The force due to the extension of the spring is

$\vec{F} = - k x = - 2 \cdot 5 = - 10 N$

The net force is

${F}_{\text{net}} = \vec{w} + \vec{F} = 39.2 - 10 = 29.2 N$