A 2.1W iPod is used for 30 minutes. How much energy does it use? (3
2 answers:
Answer:
Energy used, E = 3780 Joules
Explanation:
It is given that,
Power, P = 2.1 W
Time, t = 30 minutes = 1800 seconds
We need to find the energy used by the iPod. The product of power and time is called energy used i.e.
E = P × t
E = 3780 Joules.
So, the energy used by the iPod is 3780 Joules. Hence, this is the required solution.
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Answer:
a) see attached, a = g sin θ
b)
c) v = √(2gL (1-cos θ))
Explanation:
In the attached we can see the forces on the sphere, which are the attention of the bar that is perpendicular to the movement and the weight of the sphere that is vertical at all times. To solve this problem, a reference system is created with one axis parallel to the bar and the other perpendicular to the rod, the weight of decomposing in this reference system and the linear acceleration is given by
Wₓ = m a
W sin θ = m a
a = g sin θ
b) The diagram is the same, the only thing that changes is the angle that is less
θ' = 9/2 θ
c) At this point the weight and the force of the bar are in the same line of action, so that at linear acceleration it is zero, even when the pendulum has velocity v, so it follows its path.
The easiest way to find linear speed is to use conservation of energy
Highest point
Em₀ = mg h = mg L (1-cos tea)
Lowest point
Emf = K = ½ m v²
Em₀ = Emf
g L (1-cos θ) = v² / 2
v = √(2gL (1-cos θ))
