The US Department of Energy has set its own targets to achieve 15% of the country's electricity from hydropower by 2030 — it is currently 7%. Elsewhere around the world, countries are pledging to meet more and more of their energy needs through renewable energy sources.
Answer:
Final velocity of the first person is 3.43m/s and that of the second person is 0.0242m/s
Explanation:
Let the momentum of the first person, the ball second person be Ma, Mb and Mc.
From the principle of the conservation of momentum, sum of the momentum before collision is equal to the sum of the momentum after collision.
Ma1 + Mb1 = Ma2 + Mb2.
The ball and the first person are both moving together with a common velocity 3.45m/s.
Let the velocity of the first person be v1
Therefore
67.5×3.45+ 0.041×3.45= 67.5v1 + 0.041×34
233.02 = 1.39+ 67.5v1
67.5v1 = 233.02 - 1.39 = 231.61
v1 = 231.61 / 67.5
v1 = 3.43m/s
The second person and the ball move together with a common velocity after catching the ball.
For the second person and the ball let their final common velocity be v
Mb2 + Mc2 = Mb3 + Mc3
0.041 × 34 + 57.5 ×0 = (57.5 + 0.041)×v
57.541v = 1.39
v = 1.39 /57.541
v = 0.0242m/s
#82
here we know that
acceleration = 2 m/s/s
time = 5 s
initial speed = 4 m/s
now we can use kinematics to find the final speed
So correct answer will be option D)
#83
here we know that
acceleration = 3 m/s/s
time = 4 s
initial speed = 5 m/s
now we can use kinematics to find the final speed
So correct answer will be option C)
#84
here we know that
acceleration = 7 m/s/s
time = 3 s
initial speed = 8 m/s
now we can use kinematics to find the final speed
So correct answer will be option C)
Answer:
12.245m3
Explanation:
The electric energy is created by The potential energy substended by the specific volume of water in dam.
Electric energy is calculated as
E= Q× V
E is Energy, Q is charge and V is Voltage
Note that this energy has been given and is 60Joules
From conservation of energy it means;
M× g×h = 60
Where M is the mass of water.
g is acceleration of free fall due to gravity which is 9.8m/S2
h is the height of water flow.
From change of subject of formula for M; we have:
M = 60/ g × h
= 60/ 9.8 × 0.5
= 12.245kg
Now how much water required means the volume of water;
Note density = mass/volume
Therefore volume = mass/density
=12.245/1= 12.245m3
Note the density of water is 1kg/m3
Impulse = mass * change in velocity (change in momentum) = Force * change in time
So, F=(m*change in v)/(change in t)
F=(60*20)/0.5=2400N
Therefore the magnitude of the average force exerted on the cyclist by the haystack is 2.4*10^3N
