Answer:
when we lower a bucket into a well to fetch water, the work done by gravity is positive since force and displacement are in the same direction.
Explanation:
Answer:
0.5kg
Explanation:
Given parameters:
Potential energy = 147J
Height = 30m
Unknown:
Mass of the bird = ?
Solution:
Potential energy is the energy due to the position of a body. Now, the expression for finding the potential energy is given as;
P.E = mgH
m is the mass
g is the acceleration due to gravity = 9.8m/s²
H is the height
147 = m x 9.8 x 30
m = 0.5kg
Answer:
Explanation:
Time taken by stone to cover horizontal distance
where t is time, h is height of whirling the stone in horizontal circle, g is gravitational constant, Substituting h for 2.1 m and g for 9.81
= 0.654654 seconds
t=0.65 s
Velocity, v= distance/time
v=10/0.65= 15.27525 m/s
v=15.3 m/s
where r is radius of circle, substituting r with 1.1m
Therefore, centripetal acceleration is
From the calculations, the power expended is 43650 W.
<h3>What is the power expended?</h3>
Now we can find the acceleration from;
v = u + at
u = 0 m/s
v = 95 km/h or 26.4 m/s
t = 6.8 s
a = ?
Now
v = at
a = v/t
a = 26.4 m/s/ 6.8 s
a = 3.88 m/s^2
Force = ma = 850-kg * 3.88 m/s^2 = 3298 N
The distance covered is obtained from;
v^2 = u^2 + 2as
v^2 = 2as
s = v^2/2a
s = (26.4)^2/2 * 3.88
s = 696.96/7.76
s = 90 m
Now;
Work = Fs
Work = 3298 N * 90 m = 296820 J
Power = 296820 J/ 6.8 s
= 43650 W
Learn more about power expended:brainly.com/question/11579192
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True because all switches use contacts to start or stop the flow of electrons in a circuit