The image shows a pendulum that is released from rest at point A. Shari tells her friend that no energy transformation occurs as
the pendulum swings between point B and point D.
What is the best response that Shari’s friend could make?
She could agree with Shari because the pendulum is at the same height and would have the same gravitational potential energy at both positions.
She could agree with Shari because the pendulum has the same amount of mechanical energy throughout its swing.
She could disagree with Shari because the pendulum converts kinetic energy into gravitational potential energy, then back into kinetic energy.
She could disagree with Shari because the pendulum converts gravitational potential energy into kinetic energy, then back into gravitational potential energy.
What is the best response that Shari’s friend could make?
She could agree with Shari because the pendulum is at the same height and would have the same gravitational potential energy at both positions.
She could agree with Shari because the pendulum has the same amount of mechanical energy throughout its swing.
She could disagree with Shari because the pendulum converts kinetic energy into gravitational potential energy, then back into kinetic energy.
She could disagree with Shari because the pendulum converts gravitational potential energy into kinetic energy, then back into gravitational potential energy.
2 answers:
Answer:
She could disagree with Shari because the pendulum converts gravitational potential energy into kinetic energy, then back into gravitational potential energy.
Explanation:
The energy of the pendulum is constantly converted from gravitational potential to kinetic, and back.
In fact:
- the gravitational potential energy of the pendulum is given by:
where m is the mass of the pendulum, g is the gravitational acceleration, and h is the height of the pendulum above the ground
- The kinetic energy of the pendulum is given by:
where v is the speed of the pendulum.
Therefore, when it is at a higher position, the pendulum has a greater potential energy, while when it is at a lower position, the pendulum has a greater kinetic energy (because its speed is higher).
In this example:
- when the pendulum swings from B to C, part of its gravitational potential energy is converted into kinetic energy (because the height decreases but the speed increases), and when the pendulum goes from C to D, the kinetic energy is converted back into gravitational potential energy (because the height increases and the speed decreases)
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Answer:
The magnetic flux through surface is Wb
Explanation:
Given :
Magnitude of magnetic field T
Radius of circle m
Angle between field and surface normal 25°
From the formula of flux,
Where angle between magnetic field line and surface normal,
area of circular surface.
Magnetic flux is given by,
Wb
Therefore, the magnetic flux through surface is Wb
This question is incomplete, the complete question is;
The vector sum of the forces acting on the beam is zero, and the sum of the moments about the left end of the beam is zero.
(a) Determine the forces and and the couple
(b) Determine the sum of the moments about the right end of the beam.
(c) If you represent the 600-N force, the 200-N force, and the 30 N-m couple by a force F acting at the left end of the beam and a couple M, what is F and M?
Answer:
a)
the x-component of the force at A is = 0
the y-component of the force at A is = 400 N
the couple acting at A is; = 146 N-m
b)
the sum of the momentum about the right end of the beam is; ∑ = 0
c)
the equivalent force acting at the left end is; F = -400J ( N)
the couple acting at the left end is; M = - 146 N-m
Explanation:
Given that;
The sum of the forces acting on the beam is zero ∑f = 0
Sum of the moments about the left end of the beam is also zero ∑ = 0
Vector force acting at A, =
+
Now, From the image, we have;
a)
∑f = 0
- 600j + 200j = 0i + 0j
+
- 600j + 200j = 0i + 0j
+ (
- 400)j = 0i + 0j
now by equating i- coefficients'
= 0
so, the x-component of the force at A is = 0
also by equating j-coefficient
- 400 = 0
= 400 N
hence, the y-component of the force at A is = 400 N
we also have;
∑ = 0
- ( 30 N-m ) - ( 0.380 m )( 600 N ) + ( 0.560 m )( 200 N ) = 0
- 30 N-m - 228 N-m + 112 Nm = 0
- 146 N-m = 0
= 146 N-m
Therefore, the couple acting at A is; = 146 N-m
b)
The sum of the moments about right end of the beam is;
∑ = (0.180 m)(600N) - (30 N-m) - ( 0.56 m)(
) +
∑ = (108 N-m) - (30 N-m) - ( 0.56 m)(400 N ) + 146 N-m
∑ = (108 N-m) - (30 N-m) - ( 224 N-m ) + 146 N-m
∑ = 0
Therefore, the sum of the momentum about the right end of the beam is; ∑ = 0
c)
The 600-N force, the 200-N force and the 30 N-m couple by a force F which is acting at the left end of the beam and a couple M.
The equivalent force at the left end will be;
F = -600j + 200j (N)
F = -400J ( N)
Therefore, the equivalent force acting at the left end is; F = -400J ( N)
Also couple acting at the left end
M = -(30 N-m) + (0.560 m)( 200N) - ( 0.380 m)( 600 N)
M = -(30 N-m) + (112 N-m) - ( 228 N-m))
M = 112 N-m - 258 N-m
M = - 146 N-m
Therefore, the couple acting at the left end is; M = - 146 N-m
