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3 years ago

Define chemical and physical changes. (

Physics

2 answers:

ZanzabumX [31]3 years ago

6 0

Chemical change is two things get chemical reaction and produce a new product.

AlladinOne [14]3 years ago

3 0

A chemical change is a change in the chemical properties of a substance, resulting in a new substance. (example: rusting iron)

A physical change only changes physical properties, and is easily reversible. It does not result in a new substance. (example: melting ice)

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A 62-kg person jumps from a window to a fire net 20.0 m directly below, which stretches the net 1.4 m. Assume that the net behav

gayaneshka [121]

Answer:

a) x = 0.098

b) x = 2.72 m

Explanation:

(a) To find the stretch of the fire net when the same person is lying in it, you can assume that the net is like a spring with constant spring k. It is necessary to find k.

When the person is falling down he acquires a kinetic energy K, this energy is equal to the elastic potential energy of the net when it is max stretched.

Then, you have:

$K=U\\\\\frac{1}{2}mv^2=\frac{1}{2}kx^2$ (1)

m: mass of the person = 62kg

k: spring constant = ?

v: velocity of the person just when he touches the fire net = ?

x: elongation of the fire net = 1.4 m

Before the calculation of the spring constant, you calculate the final velocity of the person by using the following formula:

$v^2=v_o^2+2gy$

vo: initial velocity = 0 m/s

g: gravitational acceleration = 9.8 m/s^2

y: height from the person jumps = 20.0m

$v=\sqrt{2gy}=\sqrt{2(9.8m/s^2)(20.0m)}=14\frac{m}{s}$

With this value you can find the spring constant k from the equation (1):

$mv^2=kx^2\\\\k=\frac{mv^2}{x^2}=\frac{(62kg)(14m/s)^2}{(1.4m)^2}=6200\frac{N}{m}$

When the person is lying on the fire net the weight of the person is equal to the elastic force of the fire net:

$W=F_e\\\\mg=kx$

you solve the last expression for x:

$x=\frac{mg}{k}=\frac{(62kg)(9.8m/s^2)}{6200N/m}=0.098m$

When the person is lying on the fire net the elongation of the fire net is 0.098m

b) To find how much would the net stretch, If the person jumps from 38 m, you first calculate the final velocity of the person again:

$v=\sqrt{2gy}=\sqrt{2(9.8m/s^2)(38m)}=27.29\frac{m}{s}$

Next, you calculate x from the equation (1):

$x=\sqrt{\frac{mv^2}{k}}=\sqrt{\frac{(62kg)(27.29m/s)^2}{6200N/m}}\\\\x=2.72m$

The net fire is stretched 2.72 m

5 0

3 years ago

An upright spring with a 96g mass on it is compressed 2 cm. When

Alexeev081 [22]

Answer:

I only know answer A and it's 2825.28 N/m, with rounding it's 2825.5

Explanation:

Use the m*g*h=1/2*k*x^2 equation

96*9.81*60=1/2*k*2^2

5650.56=2k

5650.56/2=2825.28N/m

8 0

3 years ago

What are the types of energies released when a candle burns?

Phantasy [73]

When a candle is burning the candle is releasing thermal and radiant energy

4 0

3 years ago

Read 2 more answers

What will happen if more solute is added than can be dissolved .

zysi [14]

The solute would then sink to the bottom and would not dissolve

3 0

3 years ago

A car generates 2,552 N and weighs 2,250 pounds. what is the rate of acceleration

Lilit [14]

Ans: a = 2.50 m/s^2

Explanation:
First convert the mass in its standard unit i.e. kilogram(kg):
2250 lbs = 1020.583kg

Next use Newton's Second law:
F = ma

Where F = 2552N
m = 1020.583kg

=> a = (2552/1020.583)
a = 2.50 m/s^2

6 0

3 years ago