Answer:
90J
Explanation:
The only time work is being done is when he lifts the box off the ground. Therefore, using the work formula, 2 x 45, you get 90J. Hope this helps someone.
Hello.
Streamlined objects are objects that rudeces ari resisternece.
Some objects are
1. ari
2. water
3. solor cars
4. some land
Have a nice day
Answer
A
Explanation:
Weight = Mass x Acceleration due to gravity
Weight = 1000 x 9.81
= 9810 or 9.81x10^ 3
We will hear the sound of siren of frequency 1553.4606 Hz.
<h3>What is Doppler Effect?</h3>
The apparent change in wave frequency brought on by the movement of a wave source is known as the Doppler effect. When the wave source is coming closer and when it is moving away, the perceived frequency changes. The Doppler effect explains why we hear a passing siren's sound changing in pitch.
according to Dopplers Effect,
![f'=[\frac{v + v_{0} }{v - v_{s} } ]f](https://tex.z-dn.net/?f=f%27%3D%5B%5Cfrac%7Bv%20%2B%20v_%7B0%7D%20%7D%7Bv%20-%20v_%7Bs%7D%20%7D%20%5Df)
![f'= [\frac{700+68.1}{700-94.8} ]* 1224](https://tex.z-dn.net/?f=f%27%3D%20%5B%5Cfrac%7B700%2B68.1%7D%7B700-94.8%7D%20%5D%2A%201224)

the frequency would be 1553.4606 Hz.
to learn more about Doppler Effect go to - brainly.com/question/9165991
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In the lens equation, the variable do represents the distance of the object from the Center of the lens.