When compared to other types of waves, electromagnetic waves differ because they are
1 answer:
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1) Gravitational potential energy: 73 500 J
2) Kinetic energy: 135 000 J
3) Mechanical energy: 208 500 J
Explanation:
1)
The gravitational potential energy of an object is the energy possessed by the object due to its position in the Earth's gravitational field, and it is given by
where
m is the mass of the object
is the acceleration of gravity
h is the height of the object relative to the ground
For the skydiver in this problem,
m = 75 kg is his mass
h = 100 m is his height above the Earth
Substituting, we find
2)
The kinetic energy of a body is the energy due to its motion, and it is given by
where
m is the mass of the body
v is its speed
For the skydiver in this problem,
m = 75 kg is his mass
v = 60 m/s is his speed
Substituting, we find the kinetic energy
3)
The mechanical energy of an object is the sum of the gravitational potential energy and the kinetic energy of the object:
where
U is the gravitational potential energy
K is the kinetic energy
For the skydiver in this problem,
U = 73,500 J is the gravitational potential energy
K = 135,000 J is the kinetic energy
Substituting, we find
Learn more about potential energy and kinetic energy:
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This question is incomplete, the complete question;
The L-ft ladder has a uniform weight of W lb and rests against the smooth wall at B. θ = 60. If the coefficient of static friction at A is μ = 0.4.
Determine the magnitude of force at point A and determine if the ladder will slip. given the following; L = 10 FT, W = 76 lb
Answer:
- the magnitude of force at point A is 79.1033 lb
- since FA < FA_max; Ladder WILL NOT slip
Explanation:
Given that;
∑'MA = 0
⇒ NB [Lsin∅] - W[L/2.cos∅] = 0
NB = W / 2tan∅ -------let this be equation 1
∑Fx = 0
⇒ FA - NB = 0
FA = NB
therefore from equation 1
FA = NB = W / 2tan∅
we substitute in our values
FA = NB = 76 / 2tan(60°) = 21.9393 lb
Now ∑Fy = 0
NA - W = 0
NA = W = 76 lb
Net force at A will be
FA' = √( NA² + FA²)
= √( (W)² + (W / 2tan∅)²)
we substitute in our values
FA' = √( (76)² + (21.9393)²)
= √( 5776 + 481.3328)
= √ 6257.3328
FA' = 79.1033 lb
Therefore the magnitude of force at point A is 79.1033 lb
Now maximum possible frictional force at A
FA_max = μ × NA
so, FA_max = 0.4 × 76
FA_max = 30.4 lb
So by comparing, we can easily see that the actual friction force required for keeping the the ladder stationary i.e (FA) is less than the maximum possible friction available at point A.
Therefore since FA < FA_max; Ladder WILL NOT slip
