Building A and B are 99m apart. A student stands at P, so that his distance from building A is 33m. After clapping his hands once, he hears several echoes. The speed of sound in air is 330m/s
Calculate the time interval between clapping his hands and hearing.
1) the first echo = ?
2) the third echo =?​

when it gains or loses electrons

the box does not move because you need to use a force greater than 300 n. you are only using 50 n. it needs to at least be 301 n for the box to move because then it is an unbalanced force and it will move the way that the greater force is pushing it. if you use only 300 n it will be a balanced force and will not move because the force you are exerting on the   box is the same as its force.

hope this !

im sorry if i went too in depth, i am going to include a link to a video on khan academy that will explain this.   hope that you like the video and that it explains more in detail to you.

that is the link.

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