(u) = 20 m/s
(v) = 0 m/s
<span> (t) = 4 s
</span>
<span>0 = 20 + a(4)
</span><span>4 x a = -20
</span>
so, the answer is <span>-5 m/s^2. or -5 meter per second</span>
I think it is "A'' 'It moves along straight lines in air and changes direction when it enters water.
Answer:
180 W
Explanation:
The work done by the man against gravity is equal to its gain in gravitational potential energy:
where
(mg) = 720 N is the weight of the man
is the change in height
Substituting,
The power he must deliver is given by
where
W = 3600 J
t = 20 s is the time taken
Substituting,
The final speed of an airplane is v = 92.95 m/s
The rate of change of position of an object in any direction is known as speed i.e. in other word, Speed is measured as the ratio of distance to the time in which the distance was covered.
Solution-
Here given,
Acceleration a= 10.8 m/s2 .
Displacement (s)= 400m
Then to find final speed of airplane v=?
Therefore from equation of motion can be written as,
v²=u²+ 2as
where, u is initial speed, v is final speed ,a is acceleration and s is displacement of the airplane. Therefore by putting the value of a & s in above equation and (u =0) i.e. the initial speed of airplane is zero.
v²= 2×10.8 m/s²×400m
v²=8640m/s
v=92.95m/s
hence the final speed of airplane v =92.95m/s
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Answer
Correct answers are 1.an increase or decrease in pressure 2.an increase or decrease in energy
Explanation
All existing matter can undergo phase change it means they may transform from one state to another. phase change of a matter may occur due to change in energy and change in pressures.
for example there is an ice cube which is a solid and if we want to change it phase into liquid water for that purpose we have to supply some energy to ice cube it means we have to give some heat to ice cube. After supplying heat energy to the ice it will turn into water it means there is phase change from solid to liquid due to supplying the heat. Similarly we can change the liquid water into solid ice cube by taking heat energy(reducing temperature) from the liquid water .
In some cases the matter doesn't want to undergo phase transformation. For example, oxygen will solidify at -361.8 degrees Fahrenheit at standard pressure.But , it can change to solid state at warmer temperatures when the pressure is increased.
