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Nana76 [90]
3 years ago
10

A) How many joules of energy does a 100-watt light bulb use per hour? Express your answer using two significant figures.

Physics
1 answer:
kenny6666 [7]3 years ago
5 0

A) 3.6\cdot 10^5 J

The power used by an object is defined as

P=\frac{E}{t}

where

E is the energy used

t is the time elapsed

In this problem, we have

P = 100 W is the power of the light bulb

t = 1 h = 3600 s is the time elapsed

Solving for E, we find the amount of energy used by the light bulb:

E=Pt = (100 W)(3600 s)=3.6\cdot 10^5 J

B) 1.1 \cdot 10^2 m/s

The kinetic energy of an object is given by

K=\frac{1}{2}mv^2

where

m is the mass

v is the speed of the object

In this problem, we have a man of mass

m = 65 kg

we want its kinetic energy to be

E=3.6\cdot 10^5 J

Therefore, we can calculate its speed from the previous formula:

v=\sqrt{\frac{2K}{m}}=\sqrt{\frac{2(3.6\cdot 10^5 J)}{65 kg}}=105.2 m/s = 1.1 \cdot 10^2 m/s

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If an astronomer wants to find and identify as many stars as possible in a star cluster that has recently formed near the surfac
Andru [333]

Answer:

<em>Infrared telescope and camera</em>

<em></em>

Explanation:

An infrared telescope uses infrared light to detect celestial bodies. The infrared radiation is one of the known forms of electromagnetic radiation. Infrared radiation is given off by a body possessing some form of heat. All bodies above the absolute zero temperature in the universe radiates some form of heat, which can then be detected by an infrared telescope, and infrared radiation can be used to study or look into a system that is void of detectable visible light.

Stars are celestial bodies that are constantly radiating heat. In order to see a clearer picture of the these bodies, <em>Infrared images is better used, since they are able to penetrate the surrounding clouds of dust,</em> and have located many more stellar components than any other types of telescope, especially in dusty regions of star clusters like the Trapezium cluster.

5 0
3 years ago
How long would it take a leopard, running at an average speed of 20 m/s to travel 500 m?
alexandr1967 [171]

Answer:

25 seconds

Explanation:

500/20

4 0
2 years ago
A garage door opener has a power rating of 350 watts. If the door is in operation for 30 seconds, how many joules of energy are
Ksju [112]
Because of the hint we can conclude what equation we need to solve this problem. We have power and duration that means that we need to express energy:

1 joule = 1watt * 1 second
or
E (energy) = P (power) * t (time duration)
E = 350 * 30 = 10500 joules.
7 0
3 years ago
While at a construction site, you see a crane lift a 1000kg steel beam up to a height of 10m in a time period of 5.0 seconds. A
storchak [24]

Answer:

Car has more power output than crane      

Explanation:

We have given that mass of the crane m = 1000 kg

Height through which crane lift the steel beam h = 10 m

Acceleration due to gravity g=9.8m/sec^2

So work done by crane W=mgh=1000\times 9.8\times 10=98000j

Time period is given as t = 5 sec

We know that power P=\frac{W}{t}=\frac{98000}{5}=19600watt

Now mass of the car = 1000 kg

Initial velocity u = 0 m /sec

Final velocity v = 10 m/sec

We know that work done is equal to the change in kinetic energy

So work done =\frac{1}{2}mv^2-\frac{1}{2}mu^2

=\frac{1}{2}\times 1000\times 10^2-\frac{1}{2}\times 1000\times 0^2=50000j

Time ids given as t = 2 sec

So power P=\frac{W}{t}=\frac{50000}{2}=25000watt

So car has more power output than crane

8 0
3 years ago
Please left home at 8 AM to spend the day at in amusement park. He arrived at the park, which was 150 KM from his house, at 10 A
antiseptic1488 [7]

Answer:

v=\frac{150km}{2h}=75\frac{km}{h}

Explanation:

We can use the equation for the speed

v=\frac{x}{t}

where x is the distance and t the time. In this case we know that the time spent was 2 hours and the distance was 150km. By replacing we have

v=\frac{150km}{2h}=75\frac{km}{h}

I hope this useful for you

regards

3 0
3 years ago
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