Answer:500hz
Explanation:
Frequency=velocity/wavelength
Frequency=1500/3
Frequency=500hz
In order to create a magnifier in convex lens, you should choose a short focal length that is lesser than 1 meter.
<h3>What is a
convex lens?</h3>
A convex lens is also referred to as converging lens and it can be defined as a type of lens that typically causes parallel rays of light with respect to its principal axis to come to a focus (converge) and form a real image.
In Science, a magnifier refer to an optical instrument that allow us to look at a very near object because its image is generally formed farther away. Thus, the image of the object appears to be much larger.
In this context, you should choose a short focal length that is lesser than 1 meter when you want to create a magnifier in convex lens because the nearer the object is to the lens, the larger would be the image formed.
Read more on convex lens here: brainly.com/question/10153605
The first one is D hunted with stone-tipped spears
The second one is A
Hope this helps
Answer:
<em>We need to (at least) apply a force of 9.8 N to move the block</em>
Explanation:
<u>Second Newton's Law</u>
If a net force 
different from zero is applied to an object of mass m, then it will move at an acceleration a, given by
If we apply a force F to an object placed on a rough surface, the only way to make it move is to beat the friction force which is given by
Where 
is the static friction coefficient and 
is the normal force exerted by the table to the object. Since there is no motion in the vertical direction the normal force equals the weight of the object:
The friction force is
Thus, we need to (at least) apply a force of 9.8 N to move the block
(52 km/hr) x (0.25 hr) x (0.621 mi/km) =
(52 x 0.25 x 0.621) mile = 8.08 miles
