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2 years ago

A newspaper turns yellow in sunlight. Is this a physical or chemical change?

1 answer:

5 0

It is a chemical change. I always think of a chemical/physical change as if you could reverse it back as it started off, for example if you stepped on a can you can reverse the can back probably not exactly like it was before but you can still reverse it so this would be a physical change, and if you baked a pizza you could not reverse the dough and everything else back.

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a train engineer started the train from a standstill and sped up to 5 meters per second, she then rounded a corner at a constant

olasank [31]

for acceleration we can define that rate of change in velocity is know as acceleration

So whenever velocity of train is changing with time we can say train is accelerating

Now here if initially train is standstill then after some time its speed is 5 m/s

so here the train is accelerated first time

Then on straight path its speed changed from 5 m/s to 10 m/s so here train gets accelerated second time

After this train chugged around a curve with same speed 10 m/s

SO here since train is moving in curve so here its direction of velocity is continuously changing and this type of acceleration is known as centripetal acceleration

SO this is accelerated Third time

Then its speed decreases and it comes to speed of 5 m/s from 10 m/s

So here it is acceleration of train for Fourth time

Then finally train comes to stop so again its speed changed from 5 m/s to 0

so this is acceleration of train Fifth time

So total train will accelerate 5 times in whole path

3 0

2 years ago

According to the momentum principle, the change in momentum of an object equals the impulse, which depends on______

3241004551 [841]

Answer: The momentum principle depends on MASS and VELOCITY.

Explanation:

The momentum principle states that net force changes the the momentum of an object where momentum is the product of the MASS of the body and it's VELOCITY.

Thus, momentum = mass(kg) ×velocity( m/s)= kgm/s ( derived unit)

Also to determine the rate of change of momentum;

Mass=m, initial velocity =u, final velocity = V and time =t

Initial momentum = mu

Final momentum = mv

Change in momentum = mv - mu

= m( v- u)

Rate of change of momentum=

m( v -u)/t --> equation 1

But V = u + at

Hence, a = v -u/t

Substitute for v -u/ t in equation 1

F = Kma, where k is constant and has the value of 1.

Therefore F = ma

Newton is the SI unit if force. It is defined as the force which gives a mass of 1kg an acceleration of 1 m/s².

IMPULSE is defined as the change of momentum of a body (mv-mu) or the product of force and time.

Thus impulse = force × time = m (v-u)

The unit is Ns ( Newton seconds) which is the same as change in momentum.

3 0

2 years ago

QUESTION 1

lina2011 [118]

Solution :

Magnetic field at the centre due to $I_P$ :

$B_1 = \frac{\mu_0 I_P}{2 \pi d}$

$B_1 = \frac{4 \pi \times 10^{-7} \times 0.2}{2 \pi d}$

$B_1 =10^{-7} \ T$

Its direction will be downwards in the plane of the paper.

Magnetic field at the centre due to $I_Q$ :

$B_2 = \frac{\mu_0 I_Q}{2 \pi d}$

$B_2 = \frac{4 \pi \times 10^{-7} \times 0.6}{2 \pi \times 0.8}$

$B_2 =1.5 \times 10^{-7} \ T$

Its direction will be upwards in the plane of the paper

Magnetic field due to the coil:

$B_3 = \frac{\mu_0 I_{coil}}{2 r}$

$B_3 = \frac{4 \pi \times 10^{-7} \times 0.5}{2 \times 0.2}$

$B_3 =3.14 \times 10^{-7} \ T$

Its direction will be rightwards.

Now the resultant of the magnetic field at the centre.

$B_{net} = \sqrt{(B_2 -B_1)^2+B^2_3}$

$B_{net} = \sqrt{(0.5 \times 10^{-7})^2+(3.14 \times 10^{-7})^2}$

$B_{net} = 3.18 \times 10^{-7} \ T$

Now the direction ,

$\tan \theta = \frac{B_2-B_1}{B_3}$

$\tan \theta = \frac{0.5 \times 10^{-7}}{3.14 \times 10^{-7}}$

Therefore $\theta = 9^\circ$ (from right to upward)

3 0

3 years ago

There are two containers of equal volumes, each filled with a different gas. Both containers have the same number of moles of ga

Gekata [30.6K]

Answer:

Molecules in container 2 has a higher pressure.

Molecules in container 2 has a greater rms speed.

Molecules in container 2 has a greater kinetic energy.

Molecules in container 2 has a greater thermal energy.

Explanation:

At constant volume and temperature, The number of moles of a gas is proportional to its pressure.

The lower the pressure, the lesser the rms speed of molecules, kinetic energy of the molecules and thermal energy of the molecules, hence the answer above.

7 0

3 years ago

The process by witch solid changes to a liquid is _____?

sergij07 [2.7K]

Its a type of phase change and it is melting.

6 0

3 years ago

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