1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
andreyandreev [35.5K]
2 years ago
10

what is the percent efficiency of a light bulb that emits 14 joules of light for every 60 joules of electric energy thst enters

it?
Physics
1 answer:
jasenka [17]2 years ago
5 0
If you're using the bulb as a source of light, then it's. 14/60 = 23.3% efficient.
If you're using it to heat a bird nest or a hamster cage, then it's. 46/60 = 76.7% efficient !
It just depends on your point of view, and what you consider 'useful' output.
You might be interested in
An object with total mass mtotal = 14.6 kg is sitting at rest when it explodes into three pieces. One piece with mass m1 = 4.9 k
zheka24 [161]

Answer: 1) 0. 2) 4.2 Kg. 3) 15.4 m/s 4) 12.9 m/s 5) 0. 6) 3.62 KJ.

Explanation:

1) Assuming that no external forces act during the collision, total momentum must be conserved. As initially the total mass was at rest, so initial momentum is zero, final momentum of all the system must be 0 also.

2) After the explosion, as mass must be conserved also, the sum of the masses of the three pieces must be equal to the original total mass, so we can write the following:

m₁ + m₂ + m₃ = M = 14.6 Kg = 4.9 Kg + 5.5 Kg + m₃

Solving for m₃, we have:

m₃ = 14.6 Kg - 4.9 Kg -5.5 Kg = 4.2 Kg.

3) and 4)

As momentum is a vector, if it is magnitude must be 0, this means that all his components must be 0 too.

So, we can write two equations, one for the x-component, and other for the y-component, as follows:

pₓ = m₁. v₁ₓ + m₂.v₂ₓ + m₃.v₃ₓ = 0

py = m₁.v₁y + m₂. v₂y + m₃. v₃y =0

Replacing by the values, and solving for v₃ₓ and v₃y, we get:

v₃ₓ = 15.4 m/s

v₃y = 12.9 m/s

v = √(15.4)²+(12.9)² = 20.1 m/s

5) As the center of mass must move as if all the mass were concentrated in this point, and we know that the total momentum must be 0, this tells us that the magnitude of the velocity of the center of mass must be 0 too.

6) As initial kinetic energy is 0, as  the mass was at rest, the increase in the kinetic energy is obtained simply adding the kinetic energy of every piece of mass gained after explosion, as follows:

K = K₁ + K₂ + K₃ = 1/2 (m₁ . v₁² + m₂.v₂² + m₃.v₃²)

Replacing by the values, we get:

K= 3.62 KJ

4 0
2 years ago
As an emergency vehicle approaches Bob and moves away from Jill, how does the actual frequency of the siren change? A) As an eme
Tamiku [17]
The correct answer is: 
<span>C) The actual frequency of the siren does not change despite appearances.

In fact, Bob will observe an increase in the apparent frequency as the emergency vehicle approaches him, while Jill will observe a decrease in the apparent frequency as the emergency vehicle moves away from him, because of the Doppler effect (the relative velocity between the observer and the source of the sound is changing), but this effect involves the apparent frequency, while the real frequency of the siren will remain the same.</span>
7 0
2 years ago
Read 2 more answers
What is the net force on a truck if the force of friction is 31 N and the force of the engine is 79 N?
Evgen [1.6K]

Answer:

Fr = 48 [N] forward.

Explanation:

Suppose the movement is on the X axis, in this way we have the force of the engine that produces the movement to the right, while the force produced by the brake causes the vehicle to decrease its speed in this way the sign must be negative.

∑F = Fr

F_{engine}-F_{brake} =F_{r}\\F_{r}=79-31\\F_{r}=48[N]

The movement remains forward, since the force produced by the movement is greater than the braking force.

3 0
2 years ago
A kangaroo jumps straight up with an initial vertical velocity of 2.4m/s. We want to find the maximum height of the jump. We can
marishachu [46]

Answer:

v  

2

=v  

0

2

​  

+2aΔxv, squared, equals, v, start subscript, 0, end subscript, squared, plus, 2, a, delta, x

Explanation:

8 0
2 years ago
Read 2 more answers
What scale can I use for two force 0.8 Newtons and 0.9 Newtons? Someone please help
kirill [66]

Answer:

Explanation:

To plot the given forces of 0.8 N and 0.9 N. It is convenient to take

0.1 N as 1 unit in Graph

For example, 1 unit in the graph is  1 cm

then take 0.1 N equivalent to 1 cm

0.8 N\equiv 8\ \text{units in graph}\\\\0.9\equiv 9\ \text{units in graph}

5 0
3 years ago
Other questions:
  • The person given credit for the first modern atomic theory was __________.
    8·1 answer
  • Which organelle acts like the transportation or circulatory system of the cell?
    5·1 answer
  • What element from the periodic table rhymes with extreme
    13·1 answer
  • How long will it take a car to accelerate from 15.2 to 23.5 m/s if the car has an average acceleration of 3.2 m/s?
    13·2 answers
  • A 52.0-kg person, running horizontally with a velocity of +3.63 m/s, jumps onto a 15.2-kg sled that is initially at rest. (a) Ig
    14·1 answer
  • Elizabeth noticed an increase of Mountain Bluebird sightings in her neighborhood. She wanted to know if there was an increase in
    7·1 answer
  • he cans have essentially the same size, shape, and mass. Which can has more energy at the bottom of the ramp
    15·1 answer
  • Depending on circumstances, there are times when divers may wish to be positively, negatively or neutrally buoyant. True. False.
    7·1 answer
  • why is it important to create pictorial and physical models before trying to solve an equation, solving a physics problem
    14·2 answers
  • Please answer this question ​
    6·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!