Question

energy equation:

$w_{ext}-|w_{k}|=\delta ke + \delta pe_{g}+\delta pe_{s}$

match the equation to the description (strike - outs indicate the term is not part of the scenario and are zero)

a block slide down a frictionless slope from rest until it encounters a spring, which it compresses, momentarily coming to rest.

a. $w_{ext}-|w_{k}|=\delta ke + \delta pe_{g}+\delta pe_{s}$
b. $w_{ext}-|w_{k}|=\delta ke + \delta pe_{g}+\delta pe_{s}$
c. $w_{ext}-|w_{k}|=\delta ke + \delta pe_{g}+\delta pe_{s}$
d. $w_{ext}-|w_{k}|=\delta ke + \delta pe_{g}+\delta pe_{s}$
e. $w_{ext}-|w_{k}|=\delta ke + \delta pe_{g}+\delta pe_{s}$

Explanation:

Step1: Analyze \(W_{ext}\)

Since there is no external force (other than gravity which is accounted for in \(\triangle PE_g\)), \(W_{ext} = 0\).

Step2: Analyze \(|W_k|\)

The slope is frictionless, so there is no work done by kinetic friction. \(|W_k|=0\).

Step3: Analyze \(\triangle KE\)

The block starts from rest and ends at rest. So, \(\triangle KE=0\).

Step4: Analyze \(\triangle PE_s\)

The spring is compressed, so \(\triangle PE_s
eq0\).

Step5: Analyze \(\triangle PE_g\)

The block moves down the slope, so \(\triangle PE_g
eq0\).

Answer:

C. \(W_{ext}-|W_{k}|=\triangle KE+\triangle PE_{g}+\triangle PE_{s}\)