The image formed is 0.25 times the size of the object and 10 cm behind the pinhole. If the height of image on screen is 6 cm what is the distance of the object from the screen?

40 cm

Explanation:

Magnification of a pinhole camera is given by;

M= height of image/ height of object

Since;

M= 0.25

Height of image = 6cm

Height of object = height of image / M

Height of object = 6/0.25 = 24 cm

Height of image/ height of object = distance of image from pinhole/ distance of object from pinhole

Since the distance of image from pinhole = 10cm

Let the distance of object from pinhole be x

6/24 = 10/x

6x = 240

x= 240/6

x = 40 cm

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.

what is the speed of a softball that travels 20m in 2secs

speed = 20/2 = 10 m/s