Substances can undergo physical changes or chemical changes. what is the difference between these two kinds of changes

2 answers:

8 0

Physical changes are those change which just externally or physically change the state of the object . for example : water boils and evaporates... here the state is just changing from liquid to vapour while the composition is the same.

chemical changes are those which bring about a change in the composition of a substance. for example: burning of paper changes into ash .

slamgirl [31]3 years ago

6 0

There are several differences between a physical and chemical change in matter or substances. A physical change in a substance doesn't change what the substance is. In a chemical change where there is a chemical reaction, a new substance is formed and energy is either given off or absorbed.

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You are the juror of a case involving a drunken driver whose 1041 kg sports car ran into a stationary 1928 kg station wagon stop

mina [271]

1. Find the force of friction between the sports car and the station wagon stuck together and the road. The total mass m = 1928kg + 1041kg = 2969kg. The only force in the x-direction is friction: F = μ*N = μ * m * g
2. Find the acceleration due to friction:
F = m*a = μ * m * g => a = μ * g = 0.6 * 9.81
3. Find the time it took the two cars stuck together to slide 12m:
x = 0.5*a*t²
t = sqrt(2*x / a) = sqrt(2 * x / (μ * g) )
4. Find the initial velocity of the two cars:
v = a*t = μ * g * sqrt(2 * x / (μ * g) ) = sqrt( 2 * x * μ * g)
5. Use the initial velocity of the two cars combined to find the velocity of the sports car. Momentum must be conserved:

m₁ mass of sports car
v₁ velocity of sports car before the crash
m₂ mass of station wagon
v₂ velocity of station wagon before the crash = 0
v velocity after the crash

m₁*v₁ + m₂*v₂ = (m₁+m₂) * v = m₁*v₁
v₁ = (m₁+m₂) * v / m₁ = (m₁+m₂) * sqrt( 2 * x * μ * g) / m₁
v₁ = 33.9 m/s

7 0

3 years ago

The development of nuclear power has provided electricity for less money, but at a cost. What may be considered a "cost" of nucl

Jlenok [28]

Nuclear power generates alot of power, ALOT. It requires Uranium and other radioactive substances to power it, which over time can degrade and become depleted. This radioactive waste would have to be placed somewhere, and it accumulates over time slowly.

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4 years ago

If the distance between two asteroids is halved, the gravitational force they exert on each other will

mamaluj [8]

Answer:

e) Be four times greater

Explanation:

Here we have to use Newton's gravitational law that relates the gravitational force between two objects with their masses ( $m_{1}$ & $m_{2}$ ) and the distance between them ( $r$ ) in the next way: