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2 years ago

What if a wave reaches a type of

2 answers:

7 0

If it hit the matter that it cannot pass through.....according to the velocity of wave..it might get reflected back....we can find sound waves reflecting back in closed rooms...because of the presence of the matter through which it cannot pass....and...it's because of this tht...echo is observed

umka21 [38]2 years ago

5 0

It is bounced back. Like echoing, it's basically the sound wave hitting the matter it can't go through and bounce back.

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A cord is used to vertically lower an initially stationary block of mass M = 3.6 kg at a constant downward acceleration of g/7.

dalvyx [7]

Answer:

(a) $W_c=127.008 J$

(b) $W_g=148.176 J$

(c) K.E. = 21.168 J

(d) $v=3.4293m.s^{-1}$

Explanation:

Given:

mass of a block, M = 3.6 kg

initial velocity of the block, $u=0 m.s^{-1}$

constant downward acceleration, $a_d= \frac{g}{7}$

$\Rightarrow$ That a constant upward acceleration of $\frac{6g}{7}$ is applied in the presence of gravity.

∴ $a=- \frac{6g}{7}$

height through which the block falls, d = 4.2 m

(a)

Force by the cord on the block,

$F_c= M\times a$

$F_c=3.6\times (-6)\times\frac{9.8}{7}$

$F_c=-30.24 N$

∴Work by the cord on the block,

$W_c= F_c\times d$

$W_c= -30.24\times 4.2$

We take -ve sign because the direction of force and the displacement are opposite to each other.

$W_c=-127.008 J$

(b)

Force on the block due to gravity:

$F_g= M.g$

∵the gravity is naturally a constant and we cannot change it

$F_g=3.6\times 9.8$

$F_g=35.28 N$

∴Work by the gravity on the block,

$W_g=F_g\times d$

$W_g=35.28\times 4.2$

$W_g=148.176 J$

(c)

Kinetic energy of the block will be equal to the net work done i.e. sum of the two works.

mathematically:

$K.E.= W_g+W_c$

$K.E.=148.176-127.008$

K.E. = 21.168 J

(d)

From the equation of motion:

$v^2=u^2+2a_d\times d$

putting the respective values:

$v=\sqrt{0^2+2\times \frac{9.8}{7}\times 4.2 }$

$v=3.4293m.s^{-1}$ is the speed when the block has fallen 4.2 meters.

6 0

3 years ago

Two buses are driving along parallel freeways that are 5mi apart, one heading east and the other heading west. Assuming that eac

Oksanka [162]

Answer:

101.54m/h

Explanation:

Given that the buses are 5mi apart, and that they are both driving at the same speed of 55m/h, rate of change of distance can be determined using differentiation as;

Let l be the be the distance further away at which they will meet from the current points;

$l=\sqrt{13^2-5^2}=12m\\\\\frac{dl}{dt}=-(55m/h+55m/h})\\\\=-110m/h$ #The speed toward each other.

$\frac{dh}{dt}=0, \ \ \ \ h=constant\\\\h^2+l^2=b^2\\\\2h\frac{dh}{dt}+2l\frac{dl}{dt}=2b\frac{db}{dt}\\\\2\times5\times0+2\times12\times(-110)=2\times13\frac{db}{dt}\\\\\frac{db}{dt}=-101.54m/h$

Hence, the rate at which the distance between the buses is changing when they are 13mi apart is 101.54m/h

4 0

2 years ago

A sample of gas at 23°C is placed in an expandable container with a volume of 23 mL. The gas is heated and expands to a volume o

myrzilka [38]

Based on the options given, the most likely answer to this query is B) The temperature must be converted to Kelvin. Meaning, the temperature should be in SI unit.

Thank you for your question. Please don't hesitate to ask in Brainly your queries.

8 0

3 years ago

"the velocity of the block is constant, so the net force acting on the block must be zero. Thus the normal force equals the weig

RSB [31]

Answer:

Explanation:

"the velocity of the block is constant, so the net force acting on the block must be zero. Thus the normal force equals the weight and the force of friction equals the applied force" The only thing which is wrongly stated here is that the normal force equals the weight. Normal force is not always equal to weight. If external force is applied at some angle with the horizon , normal force may be more or less than weight. Even in case of an object placed on an inclined plane , weight is not equal to normal force .

All other parts of the statement are correct.

6 0

2 years ago

The _______ principle encourages us to resolve a set of stimuli, such as trees across a ridgeline, into smoothly flowing pattern

LenKa [72]

If this question has the same set of options as to the following, the answer would be letter d. Continuity.
Continuity in Psychology accounts for visual perception of immediate environments that piece together a background's individual elements to form a panoramic image. 

The choices are:
A.) depth perception.
B.) perception. 
C.) similarity. 
D.) continuity.

3 0

2 years ago

Read 2 more answers