Describe a simple experiment to show that sound cannot propagate through vacuum

-- Put an alarm clock or a small radio into a jar.

-- Close and seal the jar air-tight.

-- While you're listening to the clock or the radio making sound, start removing the air from the jar with some kind of vacuum machine.

-- Listen to what happens to the sound as the amount of air in the jar becomes less and less.  

weight of the box is given as

here this is placed on the inclined of angle 42 degree

now this weight will have two components one is along the incline other is perpendicular to it

so here we need to apply a force parallel to incline opposite to its component of weight

so here the component of weight is given as

here we have

so it requires 75 n force to move it upwards