Answer:
f =-20 cm
Explanation:
Given that,
The magnification of a spherical mirror, m = -1
The image distance, v = 40 cm (for negative magnification)
The magnification of a concave mirror is negative. The mirror showing -1 magnification is a concave mirror.
Let f be the focal length of the mirror. We know that,
Object distance, u = -40 cm
Using mirror's formula i.e.
So, the focal length of the mirror is 20 cm.
When towing a skier with a personal water craft with an
observer on board, the people in the personal water craft must only carry three
to five people for there is only a limited space of people to be carried on
board for it could cause conflict on board when there a lot of people of board.
Answer:
the correct one is the third :
can travel through a region void of matter and mechanical waves cannot
Explanation:
Mechanical waves travel supported by a material medium, for example sound waves travel in air, the wave on a string travels on the string.
Electromagnetic waves are produced by the variation of electric and magnetic fields, after producing this variation by the lenz law the variation of one field induces the other, so these waves do not need a material medium to travel.
Of the final statements the correct one is the third :
can travel through a region void of matter and mechanical waves cannot
a). We could read off the period if we had the graph.
The frequency is 1/period.
b). The velocity is the first derivative of the displacement,
so it should lag the displacement by 90° .
The acceleration is the derivative of the velocity,
so that puts it 180° behind the displacement.
c). If we could see the graph, then, knowing the pendulum's
length and the period of its swing, we could calculate the
acceleration of gravity on the planet at which he is at.
The number of 'G-forces' is
9.8 m/s² / (acceleration of gravity where he is at) .
The number is a ratio ... without units.
