Explanation:
Contact force is any force that requires contact. An object that exerts a force on another object by touching it is exerting a contact force. Examples of contact force are friction and normal force.
Examples of a non-contact force are gravity and magnetism.
24hours is the correct answer
In the first direct detection of gravitational waves by LIGO in 2015, the waves came from the merger of two black holes. Option B is correct. This is further explained below.
<h3>What are gravitational waves?</h3>
A gravitational wave is simply defined as a ripple in space that is unseen though extremely rapid. Gravitational waves move at light speed. As they pass past, these waves compress and stretch everything in their path.
In conclusion, the merger of two black holes is the first direct detection of gravitational waves.
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Sound waves are known to be the one that's not considered as a type of electromagnetic energy. As for microwaves and x-rays, they tend to share the same frequencies that can be considered as electromagnetic, and sound waves have a different frequency than them.
<span>The proper </span><span>battery cable connection when jumping two automotive batteries is : </span><span>(a) negative to negative / positive to positive.
</span><span>Connect the red (positive) cable from the car with the bad battery to the red (positive) on the good battery. </span>
<span>Then connect the black (negative) from the good battery to a grounding point on the other car which should be tightened and metal should be clean.
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<span>Once the car with bad battery has started, the removal of the cable should be in the opposite order. The Red (positive) which was the the First Cable to go on should be the last cable to be taken off.</span>
