In the first figure here, a sled is held on an inclined plane by a cord pulling directly up the plane. The sled is to be on the
verge of moving up the plane. In the second figure, the magnitude F required of the cord's force on the sled is plotted versus the coefficient of static friction μs between sled and plane: F1 = 2.2 N, F2 = 4.5 N, and μ2 = 0.512. At what angle θ (in ˚) is the plane inclined?
When it says something like 'on the verge of moving,' it means that the pulling force and static friction force and gravitational force all cancel out! Any more pulling force and it is ready to move!
At some point, you want F as a function of <span>μs</span>, to determine the force needed depending on the coefficient of static friction. This function, <span>F(<span>μs</span>)</span>, will rely on the angle θ as well, but we want to consider just one angle θ in every scenario. One value means it is constant.
But if we know the F, and we know <span>μs</span>, we can find what the constant angle θ must be!
If F is the pulling force, <span>FS</span> is the static friction force, and <span>FG</span> is gravitational force,
<span><span><span>Fnet</span>=0</span><span>=F+<span>FS</span>+<span>FG</span></span><span>=F+<span>FN</span><span>μs</span>+mgsinθ</span><span>=F+mgcosθ<span>μs</span>+mgsinθ</span><span>=0</span></span>
Then you can find <span>F(<span>μs</span>)</span>, but then there is the issue of solving for the θ<span> to make it true.</span>
Let's assume that ground level is the height 0 meters. The change in potential energy is going to be gravitational potential energy, which is given by PE=mgh. ΔPE=mgh-mgy =mg(h-y) =50(28-0) =1400 J
It is overhead at the equator, it is because the sun ray’s
will be moving vertically as this will be directed at the equator. It is
because if it moves vertically, it will hit or overhead the equator and this
usually happens in spring and fall.
The easiest way to get a fairly accurate measure of your water flow rate is to time yourself filling up a bucket. So for example if you fill up a 10 litre bucket in 1.5 minutes, then your flow rate will be: 10/1.5 = 6.66 Litres per minute.
