Answer:
4.5s
Explanation:
u=30m/s
v=50m/s
s=180m
a=constant(given)
By third equation of motion, v
2
=u
2
+2as
(50)
2
=(30)
2
+2a(180)
a=
3
40
m/s
2
By first equation of motion, v=u+at
50=30+(
9
40
)t
t=
2
9
=4.5sec
Answer:
350x
Explanation:
In a microscope the objective has higher magnification than the eyepiece so, this is a microscope
The magnification of a microscope is given by the product of the magnifications of the eyepiece and and the objective.
Objective lens magnification = 35x =
Eyepiece magnification = 10x =
Total magnification
Total magnification is 350x
Sure. The acceleration may be decreasing, but as long as it stays
in the same direction as the velocity, the velocity increases.
I think you meant to ask whether the body can have increasing velocity
with negative acceleration. That answer isn't simple either.
If the body's velocity is in the positive direction, then positive acceleration
means speeding up, and negative acceleration means slowing down.
BUT ... If the body's velocity is in the negative direction, then positive
acceleration means slowing down, and negative acceleration means
speeding up.
I know that's confusing.
-- Take a piece of scratch paper, write a 'plus' sign at one edge and
a 'minus' sign at the other edge. Those are the definitions of which
direction is positive and which direction is negative.
-- Then sketch some cars ... one traveling in the positive direction, and
one driving in the negative direction. Those are the directions of the
velocities.
-- Now, one car at a time:
. . . . . first push on the back of the car, in the direction it's moving;.
. . . . . then push on the front of the car, against its motion.
Each push causes the car to accelerate in the direction of the push.
When you see it on paper, all the positive and negative velocities
and accelerations will come clear for you.
Answer:
15 meters
Explanation:
The inicial energy of the ball is just potencial energy, and its value is:
E = m * g * h = m * g * 20,
where m is the ball mass, and g is the value of gravity.
In the moment that the ball strickes the ground, all potencial energy transformed into kinetic energy, and 25% of this energy is lost, so the total energy at this moment will be:
E' = 0.75 * E = 0.75 * m * g * 20 = 15*m*g
This kinetic energy will make the ball goes up again, and at the maximum height, all kinetic energy is transformed back into potencial energy.
So, as the mass and the gravity are constants, we can calculate the height the ball will reach:
E' = m*g*h = 15*m*g -> h = 15 meters
Answer:
Red giant or super giant → very cool but very luminous
→ found in the upper right of the H-R diagram.
Main sequence →The majority of stars in our galaxy
→ Sun, for example
→ a very hot and very luminous star
White dwarfs → very hot but very dim
→ not much larger in radius than earth
Explanation:
Giant:
When the stars run out of their fuel that is hydrogen for the nuclear fusion reactions then they convert into Giant stars.That's why they are very cool. Giant stars have the larger radius and luminosity then the main sequence stars.
Main Sequence:
Stars are called main sequence stars when their core temperature reaches up to 10 million kelvin and their start the nuclear fusion reactions of hydrogen into helium in the core of the star. That is why they are very hot and luminous. For example sun is known as to be in the stage of main sequence as the nuclear fusion reactions are happening in its core.
White dwarfs:
When the stars run out of their fuel then they shed the outer layer planetary nebula, the remaining core part that left behind is called as white dwarf. It's the most dense part as the most of the mass is concentrated in this part.
