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.
Correct Answers is A.
The machines gives us some mechanical advantage. This means the mechanical average makes the work output greater than the work input
Simple most example is a lever. The force applied is smaller and the output work is larger as compared to input.
Option B cannot be true, as there must be a force to get some work done.
Option C and D are inverse of what a machine is designed for. A small force can be exerted through a large distance to have a large force exerted through a small distance. Common Example of this principle is a screw opener.
Answer:
Explanation:
The horizontal component of force applied = 7.97 cos 26.2 = 7.15 N.
Vertical component in upward direction = 7.97 sin 26.2 = 3.52 N.
Since the body is moving with uniform velocity, friction force will equalize the external horizontal component = 7.15 N.
So frictional force = 7.15 N.
a) Work done by rope force per second = force in horizontal direction x displacement per second = 7.15 x 4.33 = 30.95 J
b) Increase in thermal energy per second will be due to negative work done by frictional force = work done by external force = 30.95 J.
c) Normal force acting downwards = weight - vertical component of external force = 4.36 x 9.8 - 3.52 = 39.21 N
coefficient of friction = friction force / normal force = 7.15 / 39.21 = 0.18
Explanation:
The energy of a wave is given by :
Where
h is Planck's constant
c is the speed of light
is wavelength
Energy is inversely proportional to wavelength. Also, the relation between frequency and wavelength is inverse.
If the frequency is high, the wavelength will be shorter.
Hence, the correct options are :
Higher frequencies have shorter wavelengths.
Shorter wavelengths have lower energy.
Lower frequencies have lower energy.
