hertz: A unit for measuring frequency, equal to one cycle per second. If a sound wave has a frequency of 20,000 Hz,
Answer:
(D) 0.99 cm
Explanation:
Given that the radius of curvature of the mirror is 25 cm.
And another car is following which is behind the mirror of 20 m.
Focal length is half of the radius of curvature and it is negative for convex lens.
Now the mirror formula.
So,
Now
Magnification is,
So,
So, Height of the image
Therefore, the image height is 0.99 cm.
Here's what you need to memorize for your exam tomorrow.
Distance = (speed) x (time) .
That's it. Memorize it.
-- If the question wants you to find speed, use it exactly in that form.
-- If the question wants you to find speed, then divide each side by (time)
and it says
. Time = (distance) / (speed) .
-- If the question wants you to find time, then divide each side by speed,
and it says
. Time = (distance) / (speed) .
So if you memorize that one equation ... Distance = (speed) x (time) ...
you can solve ANY problem to find distance, speed, or time.
On the sheet in the picture . . . . .
#2). The question is "How long ?". That's TIME that you have to find.
Use the equation in the form of
. TIME = (distance) / (speed)
. = (60 km) / (48 km/h)
. = 1.25 hours .
#3). This one wants you to find SPEED. Use the equation in the form of
. SPEED = (distance) / (time)
but be careful. The time has to be in hours. 55 minutes = 55/60 of an hour.
. SPEED = (distance) / (time)
. = (60 km) / (55/60 hour)
. = (60 x 60 km) / (55 hour)
. = 65.45 km/hr .
#4). This one wants you to find TIME. (It says "How long ?".)
It's two trips, so you have to find the time for each trip.
First trip: TIME = (distance)/(speed) = (24 km)/(65 km/hr) = 0.369 hr
Second trip: TIME = (distance)/(speed) = (50 km)/(80 km/hr) = 0.625 hr
Total time for both trips = (0.369 hr) + (0.625 hr) = 0.994 hour
Apart from cutaneous respiration<span> present in all </span>species<span>, most lissamphibians are born in an aquatic larval stage with gills. After metamorphosis, they develop lungs to breathe on land. The larvae of urodeles and apods present external, filamentous and highly branched gills which allow them to breathe underwater.
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