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4 years ago

An endothermic reaction will start when the required ΔH energy is received from the environment or solution. True or False.

Physics

2 answers:

iren [92.7K]4 years ago

6 0

Answer: A ) ΔH

Explanation:

34kurt4 years ago

5 0

<span>An endothermic reaction will start when the required ΔH energy is received from the environment or solution this is false as the reaction may require energy in excess to start the reaction</span>

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Which one of the following statements best illustrates implicit memory?

Temka [501]

I believe the answer is A. <span>At age 40, after 15 years, George got on his old bike and found he could still ride it without falling on his face.
Implicit memory is the type of memory that we've acquired in the past and often used automatically/subconsciously.
Other examples of implicit memory is when we could do a certain task that we're used to do even without paying any attention.</span>

8 0

3 years ago

While tuning a string to the note C at 523 Hz, a piano tuner hears 2.00 beats/s between a reference oscillator and the string.

lara31 [8.8K]

Answer:

a)the possible frequencies are 521hz ,522hz, 523, 524hz,525hz

b) 526hz

c)0.989 or a 1.14% decrease in tension

Explanation:

a) While tuning a string at 523 Hz,piano tuner hears 2.00 beats/s between a reference oscillator and the string.

The possible frequencies of the string can be calculated by

fl=f' - B

where

fl= lower limit of the possible frequency

f'= frequency of the string

B= beat heard by the tuner

fl= 523hz + Or - (2beats/secs * 1hz/1beat per sc)

fl= 521hz or 525hz

So the possible frequencies are 521hz ,522hz, 523, 524hz,525hz

b)fl=f' - B

523hz= f' - 3

f'= 523 + 3= 526hz

c) The tension is directly proportional to the square of the frequencies

T1/T2 =f1^2/f2^2

523^2 / 526^2 = 0.989 or a 1.14% decrease in tensio

6 0

3 years ago

Moving company uses a machine to raise a 900 Newton refrigerator to the second floor of a building machine consists of a single

Juliette [100K]

Mechanical advantage of a machine is the ratio of the output force over the input force or M=Fo/Fi. Since M=1, Fi=Fo, or the input force is equal to the output force. This means that to raise the refrigerator that weighs 900 N, we need the same input force of 900 N, or Fo=Fi=900 N.

6 0

3 years ago

Read 2 more answers

A leaky 10-kg bucket is lifted from the ground to a height of 11 m at a constant speed with a rope that weighs 0.9 kg/m. Initial

nalin [4]

Answer:

the work done to lift the bucket = 3491 Joules

Explanation:

Given:

Mass of bucket = 10kg

distance the bucket is lifted = height = 11m

Weight of rope= 0.9kg/m

g= 9.8m/s²

initial mass of water = 33kg

x = height in meters above the ground

Let W = work

Using riemann sum:

the work done to lift the bucket =∑(W done by bucket, W done by rope and W done by water)

= $\int\limits^a_b {(Mass of Bucket + Mass of Rope + Mass of water)*g*d} \, dx$

Work done in lifting the bucket (W) = force × distance

Force (F) = mass × acceleration due to gravity

Force = 9.8 * 10 = 98N

W done by bucket = 98×11 = 1078 Joules

Work done to lift the rope:

At Height of x meters (0≤x≤11)

Mass of rope = weight of rope × change in distance

= 0.8kg/m × (11-x)m

W done = integral of (mass×g ×distance) with upper 11 and lower limit 0

W done = $\int\limits^1 _0 {9.8*0.8(11-x)} \, dx$

Note : upper limit is 11 not 1, problem with math editor

W done = 7.84 (11x-x²/2)upper limit 11 to lower limit 0

W done = 7.84 [(11×11-(11²/2)) - (11×0-(0²/2))]

=7.84(60.5 -0) = 474.32 Joules

Work done in lifting the water

At Height of x meters (0≤x≤11)

Rate of water leakage = 36kg ÷ 11m = $\frac{36}{11}$ kg/m

Mass of rope = weight of rope × change in distance

= $\frac{36}{11}$ kg/m × (11-x)m = 3.27kg/m × (11-x)m

W done = integral of (mass×g ×distance) with upper 11 and lower limit 0

W done = $\int\limits^1 _0 {9.8*3.27(11-x)} \, dx$

Note : upper limit is 11 not 1, problem with math editor

W done = 32.046 (11x-x²/2)upper limit 11 to lower limit 0

W done = 32.046 [(11×11-(11²/2)) - (11×0-(0²/2))]

= 32.046(60.5 -0) = 1938.783 Joules

the work done to lift the bucket =W done by bucket+ W done by rope +W done by water)

the work done to lift the bucket = 1078 +474.32+1938.783 = 3491.103

the work done to lift the bucket = 3491 Joules

8 0

4 years ago

Which statement is correct about an element’s identifying spectrum? a) The light reflected off an element produces a unique iden

Ronch [10]

Answer:

correct answer is option d (Light emitted by an element produces a unique identifying spectrum.)

Explanation:

Each element has different atomic number and atoms of an element can radiate a certain amount of energy. Different elements have different atomic spectrum and it can be used to determine the composition of a material.

When atoms are excited to higher energy state after some time they came back to lower state by emitting their excess energy in the form of light. This light has certain wavelength. This emitted light can be seen as a series of different colored lines and between two colored lines there is a dark space. This series of colored lines is called a line spectra or atomic spectra.

3 0

3 years ago

Read 2 more answers