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3 years ago

A nail driven into a board increases in temperature.

Physics

1 answer:

denis23 [38]3 years ago

5 0

Answer:

ΔT = 40.91 °C

Explanation:

First we find the kinetic energy of one hit to the nail:

K.E = (1/2)mv²

where,

K.E = Kinetic energy = ?

m = mass of hammer = 1.6 kg

v = speed of hammer = 7.7 m/s

Therefore,

K.E = (1/2)(1.6 kg)(7.7 m/s)²

K.E = 47.432 J

Now, for 10 hits:

K.E = (10)(47.432 J)

K.E = 474.32 J

Now, we calculate the heat energy transferred (Q) to the nail. As, it is the 59% of K.E. Therefore,

Q = (0.59)K.E

Q = (0.59)(474.32 J)

Q = 279.84 J

The change in energy of nail is given as:

Q = mCΔT

where,

m = mass of nail = 7.6 g = 0.0076 kg

C = specific heat capacity of aluminum = 900 J/kg.°C

ΔT = Increase in temperature = ?

Therefore,

279.84 J = (0.0076 kg)(900 J/kg.°C)ΔT

ΔT = (279.84 J)/(6.84 J/°C)

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A person runs 15 kilometers in two hours what is his/her average speed

bazaltina [42]

Answer:

$\displaystyle V=7.5\ km/h$

Explanation:

<u>Average Speed </u>

If an object travels a distance d in a time t regardless of the direction, the average speed is the quotient of the distance over the time:

$\displaystyle V=\frac{d}{t}$

It's known a person runs d=15 kilometers in t=2 hours, thus his/her average speed is:

$\displaystyle V=\frac{15\ km}{2\ h}$

Calculating:

$\boxed{\displaystyle V=7.5\ km/h}$

5 0

3 years ago

It’s for a cross word and mechanical doesn’t fit ☹️

VikaD [51]

Answer:

Circular wave

Explanation:

Circular waves are special types of mechanical waves. They all travel through a material medium or some times a vacuum.

An example of such wave is a ripple caused by dropping a stone in a tank of water.

A wave that propagates in circular form on the surface of water falls into this category.

6 0

3 years ago

Two identical vertical springs S1 and S2 have masses m1 = 400 g and m2 = 800 g attached to them. If m1 causes spring S1 to stret

OlgaM077 [116]

Answer:

potential energy = mgh

= 400÷1000 × 10× 4÷100

= 0.4 × 10 × 0.04

=4/10 ×10×4/100

= 4/10 × 4/10

=16/100

= 0.16 joules

m1 (400) stretches 4cm

m1 (100g) stretches 1cm

so, m2(800g) stretches 8 cm

potential energy of m2 = mgh

= 800/1000 ×10×8/100

= 0.8 × 0.8

=8/10 ×8/10

= 64/100

=0.64 joules

Ratio of s1 to s2

16/100 ÷ 64/100

= 1:4 ( answer)

6 0

2 years ago

If a 4 engine jet accelerates down a runway at 8.7 m/s^2, Suppose now that all 4 engins are operational on the jet from the prev

soldi70 [24.7K]

Answer:

$5.22m/s^2$

Explanation:

One of the first propulsion characteristics given in the example is that all engines are equal.

In this way if we have 4 engines running at the same time, it means that its capacity is 100%.

Under this premise, if 100% is found, the Jet is capable of reaching a speed of 8.7m / s ^ 2.

However, the question is, what would happen if 2.4 "Engines" now work.

To do this then we make a simple equivalence,

If 4 engines is the equivalent of 100%, when would it be 2.4 engines?

$X = \frac{2.4 * 100\%} { 4 }= 60\%$

In this way it would mean that the body could be driven to 60% of its total.

$Speed_{Decreased} = 8.7 * 60\% = 5.22 \frac{m}{s^2}$

3 0

3 years ago

a stone is thrown vertically upwards with a velocity of 20 m per second what will be its velocity when it reaches a height of 10

TEA [102]

Answer:

Explanation:

Here's the info we have:

initial velocity is 20 m/s;

final velocity is our unknown;

displacement is -10.2 m; and

acceleration due to gravity is -9.8 m/s/s. Using the one-dimensional equation

v² = v₀² + 2aΔx and filling in accordingly to solve for v:

$v=\sqrt{(20)^2+2(-9.8)(-10.2)}$ Rounding to the correct number of sig fig's to simplify:

$v=\sqrt{400+2.0*10^2}$ to get

v = $\sqrt{600}=20\frac{m}{s}$ If you don't round like that, the velocity could be 24, or it could also be 24.5 depending on how your class is paying attention to sig figs or if you are at all.

So either 20 m/s or 24 m/s

7 0

3 years ago