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3 years ago

A girl runs 40m due south in 40 seconds an d then 20m due north in 10 secondsCalculate.

Physics

1 answer:

m_a_m_a [10]3 years ago

3 0

Answer:

Average speed = 1.2 m/s

Average velocity = 0.4 m/s

Explanation:

Average speed = total distance/total time

Average speed = (40 + 20)/(40 + 10)

Average speed = 60/50

Average speed = 1.2 m/s

Average velocity = displacement/time

Now, she ran 40 m south and ran 20 m back north which is in the direction of where she began the journey.

Thus;

Displacement = 40 - 20 = 20 m

Average velocity = 20/50 = 0.4 m/s

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A pilot heads his jet due east. The jet has a speed of 425 mi/h relative to the air. The wind is blowing due north with a speed

Alja [10]

Answer:

(a)Velocity of wind = 35 j

(b)Velocity of jet relative to air = 425 i

(c)True velocity of jet = 425 i + 35 j

(d)True speed of jet = $\sqrt{425^{2}+35^{2}}$ = 426.88 mi/h

Direction of jet is, ∅ = $tan^{-1} \frac{40}{425}$ = 5.38°

Explanation:

We can represent east direction by i and north direction by j.

The jet has a relative speed of 425 mi/h relative to the air.

The wind is blowing due north with a speed of 35 mi/h = 35 j

425 mi/h is the relative speed with respect to wind that is

Velocity of jet wrt wind= $V_{jw}$ = $V_{j}-V_{w}$

425 i = $V_{j}$ - 35 j

$V_{j}$ = 425 i + 35 j

(a)Velocity of wind = 35 j

(b)Velocity of jet relative to air = 425 i

(c)True velocity of jet = 425 i + 35 j

(d)True speed of jet = $\sqrt{425^{2}+35^{2}}$ = 426.88 mi/h

Direction of jet is,

∅ = $tan^{-1} \frac{40}{425}$ = 5.38°

7 0

3 years ago

An astronomy student, for her PhD, really needs to estimate the age of a cluster of stars. Which of the following would be part

LiRa [457]

Answer:

A. plot an H-R diagram for the stars in the cluster.

Explanation:

A star cluster can be defined as a constellation of stars, due to gravitational force, which has the same origin.

The astronomy student would have to plot an H-R diagram for the stars in the cluster and determine the age of the cluster by observing the turn-off point. The turn-off is majorly as a result of gradual depletion of the source of energy of the star. Thus, it projects off the constellation.

4 0

2 years ago

Two steamrollers begin 115 mm apart and head toward each other, each at a constant speed of 1.10 m/sm/s . At the same instant, a

NeX [460]

Answer:

The distance of fly travel is 115.06 m.

Explanation:

Given that,

Distance = 115 mm

Speed = 1.10 m/s

Speed of fly = 2.20 m/s

We need to calculate the relative speed

Using formula of relative speed

$v=v_{1}+v_{2}$

Put the value into the formula

$v=1.10+1.10$

$v=2.20\ m/s$

We need to calculate the time for the two steamrollers to meet each other

Using formula of time

$t=\dfrac{d}{v}$

Put the value into the formula

$t=\dfrac{115}{2.20}$

$t=52.3\ sec$

We need to calculate the distance of fly travel

Using formula of distance

$d=vt$

Put the value into the formula

$d=2.20\times52.3$

$d=115.06\ m$

Hence, The distance of fly travel is 115.06 m.

3 0

3 years ago

Which surface has the most friction? a An ice rink b A grassy field c A paved road

vovangra [49]

Answer:

An Ice Rink

Explanation:

7 0

2 years ago

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If you were stuck in the center of the bridge when it was swaying, where would be the safest place to walk back to land?

Ludmilka [50]

Straight
You already have to momentum of walking forward, and going back and forth are the same distance. If you go back then you would have to stop, turn and walk, but if you go forward you just have to walk.

4 0

3 years ago