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Andrew [12]
3 years ago
11

how long does it take a 750watt heater operating at full rating to rais the temperature of 1kg of water From 40°C to 70°C {S.H.C

=4200j/kg/k and neglecte heat loss}​
Physics
1 answer:
siniylev [52]3 years ago
6 0

Answer:

168 seconds (2 min 48 s)

Explanation:

Find the heat absorbed by the water.

q = mCΔT

q = (1 kg) (4200 J/kg/K) (70°C − 40°C)

q = 126,000 J

Power is energy per time.

P = q / t

750 W = 126,000 J / t

t = 168 s

It takes 168 seconds (2 min 48 s).

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Help me with the question in the image I provided​
inna [77]

Answer: 10 s, 30 m/s , 150 m

Explanation:

Given

The speed of motorcyclist is  u_1=15\ m/s

The initial speed of a police motorcycle is u_2=0\ m/s

acceleration of police motorcycle is a=3\ m/s^2

Police will catch the motorcyclist when they traveled equal distances

distance traveled by motorcyclist in time t is

\Rightarrow s_1=15\times t

Distance traveled by Police in time t is

\Rightarrow s_2=u_2t+\frac{1}{2}at^2\\\Rightarrow s_2=0+0.5\times 3\times t^2

put s_1=s_2

\Rightarrow 15t=0.5\times 3\times t^2\\\\\Rightarrow t(1.5t-15)=0\\\\\Rightarrow t=\dfrac{15}{1.5}=10\ s

Police officer's speed at that time is

\Rightarrow v_2=u_2+at\\\Rightarrow v_2=0+3\times 10=30\ m/s

Distance traveled by each vehicle is

\Rightarrow s_1=s_2=15\times t=15\times 10=150\ m

8 0
2 years ago
Which statements does the Second Law of Thermodynamics support?
Mazyrski [523]
According to the second law of thermodynamics, 
the answer is 
<span>4. The entropy of the universe is increasing. </span>
4 0
3 years ago
What is the direction of the magnetic field if an electron moving in the positive x direction experiences a magnetic force in th
Alex787 [66]

Given :

An electron moving in the positive x direction experiences a magnetic force in the positive z direction.

To Find :

The direction of the magnetic field.

Solution :

We know, force is given by :

\vec{F}=q(\vec{v}\times \vec{B)}

Here, q = -e.

\vec{F}=(-e)(\vec{v}\times \vec{B)}\\\\\hat{k}=(-e)(\hat{i}\times \vec{B})

Now, for above condition to satisfy :

\hat{i}\times \vec{B}=-\hat{k}

So, \vec{B}=-\hat{j}

Therefore, direction of magnetic field is negative y direction.

Hence, this is the required solution.

7 0
3 years ago
Question 5. Our results support the idea that if left to freely oscillate, a system will vibrate at a natural frequency that dep
Gekata [30.6K]

Answer:

(b) In ideal condition we neglect mass of spring but in real springs mass of spring adds another factor to its time period.

since we are adding a factor of mass to the system, and frequency being inversely proportional to squared root of mass, we can come to a general conclusion that it effectively reduces the natural frequency .

Explanation:

kindly check the attachment for explanation.

3 0
3 years ago
HELP!!
raketka [301]
Hello!

Since the two weights are <em>off</em> the table, the block will move towards letter F. 

I hope this helps :))
5 0
3 years ago
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