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skelet666 [1.2K]

3 years ago

15

Which use of a simple machine changes the direction of a force? A. using a ramp to load boxes onto a truck B. using an axe to sp

lit wood C. removing a bottle cap with a bottle opener D. lifting a rock with a crowbar

1 answer:

kiruha [24]3 years ago

8 0

A. <span> using a ramp to load boxes onto a truck </span>

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The troughs or zero amplitude of a standing wave are called ____________.

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Each successive graph is at a later time. You can see from these graphs how the amplitude of the total electric field changes, but the positions of the crests and troughs (called antinodes) and places of zero field (called nodes) never change.!!!!!!!!!!!!!!!!!

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4 years ago

find the time taken, if the speed of a train increased from 72 km/hr to 90 km/hr for 234 km. leave your answer in seconds

Airida [17]

Answer:

Time taken = 10400 s

Explanation:

Given:

Initial speed of the train, $u=72\textrm{ km/h}=72\times \frac{5}{18}=20\textrm{ m/s}$

Final speed of the train, $v=90\textrm{ km/h}=90\times \frac{5}{18}=25\textrm{ m/s}$

Displacement of the train, $S=234\textrm{ km}=234\times 1000=234000\textrm{ m}$

Using Newton's equation of motion,

$v - u = at\\a=\frac{v-u}{t}$

Now, using Newton's equation of motion for displacement,

$v^{2}-u^{2}=2aS$

Now, plug in the value of $a=\frac{v-u}{t}$ in the above equation. This gives,

$v^{2}-u^{2}=2\times \frac{v-u}{t}\times S\\(v+u)(v-u)=\frac{2(v-u)S}{t}\\t=\frac{2(v-u)S}{(v+u)(v-u)}\\t=\frac{2S}{v+u}$

Now, plug in 234000 m for $S$ , 25 m/s for $v$ and 20 m/s for $u$ . Solve for $t$ .

$t=\frac{2S}{v+u}\\t=\frac{2\times 234000}{25+20}\\t=\frac{468000}{45}=10400\textrm{ s}$

Therefore, the time taken by the train is 10400 s.

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4 years ago

What is a fact about incline planes?

SVETLANKA909090 [29]

They are incline hope this helps!

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3 years ago

Pitch describes how high or low a sound is. The pitch of a sound is most dependent upon the of the sound wave.

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Answer: C. Frequency

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3 years ago

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45. When you park on a level road next to a curb: A. Your wheels must be within 18 inches of the curb B. Your front wheels must

tekilochka [14]

Answer:

A

Explanation:

You must be within 18 inches.

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3 years ago