 Need Help?

Subscribe to Physics 1

###### \${selected_topic_name}
• Notes

$\begin{array}{l}{\text { A "moving sidewalk" in an airport terminal building moves at } 1 \mathrm{m} / \mathrm{s} \text { and is } 35.0 \mathrm{m} \text { long. If a woman steps on }} \\ {\text { at one end walks at } 1.5 \mathrm{m} / \mathrm{s} \text { relative to the moving sidewalk, how much time does she require to reach }} \\ {\text { the opposite end if she walks (a) in the same direction the sidewalk is moving?(b) In the opposite direction? }}\end{array}$

$\begin{array}{l}{V(\text { sidewalk })={1m} / \mathrm{s}} \\ {\text { dist. }=35 \mathrm{m}} \\ {\mathrm{V}(\text { women })=1.5 \mathrm{m} / \mathrm{s}} \\ {t \text { ?? }}\end{array}$

$V_{W/G}, \ V_{W/S}, \ V_{S/G}$

$V_{W / G}=V_{W / S}+V_{S/ G}$

$V=\frac{d}{t} \rightarrow V_{W/{G}}=\frac{d{i s t}}{t{i m e}}$

$\text {time}=\frac{d i s t}{V_{W/ G}}$

(a) $V_{W/G}=V_{W/S}+V_{S / G}$

$\rightarrow \quad V_{W / G}=1.5+1=2.5 \mathrm{m} / \mathrm{s}$

$\longrightarrow \text { time }=\frac{d i s t}{V_{W/G}}=\frac{35}{2.5}=14 \mathrm{s}$

(b) $V_{W / G}=V_{W / S}+V_{S / G}$

$\rightarrow V_{W/G}=-1.5+1 =-0.5 \mathrm{m} / \mathrm{s}$

$\longrightarrow \text { time }=\frac{d i s t}{V_{W/G}}=\frac{-35}{-0.5}=70s$

$\begin{array}{l}{\text { A rairoad flatcar is traveling to the right at a speed of } 13 \mathrm{m} / \mathrm{s} \text { relative to an observer standing on the }} \\ {\text { gromeone is riding a moto scooter on the flactear. What is the velocity (magnitude and direction) }} \\ {\text { of the motor scoter ritive to the flatcar if its velocity relative to the observer on the ground is }} \\ {\text { (a) } 18 \mathrm{m} / \mathrm{s} \text { to the right? }(\mathrm{b}) 3.0 \mathrm{m} / \mathrm{s} \text { to the left? (c) zero? }}\end{array}$

$\vec{V}_{S / F}, \ \vec{V}_{S / G}, \ \vec{V}_{F / G}$

$\vec{V}_{S / G}=\vec{V}_{S / F}+\vec{V}_{F / G} \longrightarrow \vec{V}_{S / F}=\vec{V}_{S / G}-\vec{V}_{F / G}$

(a) $\vec{V}_{S/F}=18-13=5 \mathrm{m}/ \mathrm{s}$ to the Right

(b) $\vec{V}_{S/F}=-3-13=-16 \mathrm{m} / \mathrm{s}=16 \mathrm{m} / \mathrm{s}$ to the left

(c) $\vec{V}_{S/F}=0-13=-13 m / s=13 \mathrm{m} / \mathrm{s}$  to the left