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strojnjashka [21]
3 years ago
9

The modern periodic table has______ groups. (Write your answer as a number.)

Physics
2 answers:
ss7ja [257]3 years ago
5 0
I think it has 18 groups
kobusy [5.1K]3 years ago
4 0
It contains 18 groups
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It requires 2,500 joules to raise a certain amount of water (c = 4.186 J/g C) from 20 C to 60 C
Ksivusya [100]

The mass of the water is 14.9 g

Explanation:

When a certain amount of a susbtance is heated, the temperature of the substance increases according to the equation

Q=mC_s \Delta T

where

Q is the amount of energy supplied to the substance

m is the mass of the substance

C_s is its specific heat capacity

\Delta T is the change in temperature

In this problem, we have:

Q = 2500 J of energy supplied to the water

C_s = 4.186 J/gC is the specific heat capacity of water

\Delta T=60 C - 20 C = 40^{\circ}C is the change in temperature of the water

Therefore we can solve for m to find the mass of the water:

m=\frac{Q}{C_s \Delta T}=\frac{2500}{(4.186)(40)}=14.9 g

Learn more about specific heat capacity:

brainly.com/question/3032746

brainly.com/question/4759369

#LearnwithBrainly

7 0
3 years ago
The speed of sound through diamond is about 12,000 m/s. The speed of sound through wood is about 3,300 m/s. Which statement expl
Damm [24]

Answer: They have different rigidities.

Explanation:

7 0
2 years ago
What is the direction and speed of an object?
KatRina [158]

Answer:

Explanation:

Velocity by definition means speed and direction of an object. This means it has a value and a positive or minus sign indicating direction. Speed is the absolute value of velocity because there is no direction correlated with speed. If you add a direction, it is then called velocity

7 0
3 years ago
Tourists covered 255 km for a 4-hour ride by car and a 7-hour ride by train. what is the speed of the train, if it is 5 km/h gre
LekaFEV [45]
The distance covered by car is equal to (assuming it is moving by uniform motion) the product between the car's speed and the time of the car ride, 4 h:
S_c = v_c t_c
where
v_c is the car's speed
t_c = 4 h is the duration of the car ride

Similarly, the distance covered by train is equal to the product between the train's speed and the duration of the train ride, 7 h:
S_t = v_t t_t

The total distance covered is S=255 km, which is the sum of the distances covered by car and train:
S=255 km = S_c + S_t
which becomes
255 = 4 v_c + 7 v_t (1)
we also know that the train speed is 5 km/h greater than the car's speed:
v_t = 5 + v_c (2)

If we put (2) into (1), we find
255 = 4v_c + 7(5+v_c)
and if we solve it, we find
v_c = 20 km/h
v_t = 25 km/h

So, the car speed is 20 km/h and the train speed is 25 km/h.

4 0
3 years ago
I stretch a rubber band and "plunk" it to make it vibrate in its fundamental frequency. I then stretch it to twice its length an
Nikitich [7]

Answer:

The new frequency (F₂ ) will be related to the old frequency by a factor of one (1)

Explanation:

Fundamental frequency = wave velocity/2L

where;

L is the length of the stretched rubber

Wave velocity = \sqrt{\frac{T}{\frac{M}{L}}}

Frequency (F₁) = \frac{\sqrt{\frac{T}{\frac{M}{L}}}}{2*L}

To obtain the new frequency with respect to the old frequency, we consider the conditions stated in the question.

Given:

L₂ =2L₁ = 2L

T₂ = 2T₁ = 2T

(M/L)₂ = 0.5(M/L)₁ = 0.5(M/L)

F₂ = \frac{\sqrt{\frac{2T}{0.5(\frac{M}{L})}}}{4*L} = \frac{\sqrt{4(\frac{T}{\frac{M}{L}}})}{4*L} = \frac{2}{2} [\frac{\sqrt{\frac{T}{\frac{M}{L}}}}{2*L}] = F_1

Therefore, the new frequency (F₂ ) will be related to the old frequency by a factor of one (1).

7 0
3 years ago
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