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3 years ago

Why do we have thunder storms

1 answer:

3 0

Thunderstorms happen when cold air sinks and hot air rises in rapid succession. There has to be an unstable body of hot air for a thunderstorm to happen. Cool air mingles with the hot air causing condensation (that means that raindrops form) This makes a cumulous cloud.
The moisture in the cloud is either positively charged or negatively charged. Negatively charged particles sink to the bottom of the cumulous cloud while positively charges particles rise. The positive and negative charges rub together and spark causing lightning.
Thunder is formed by the lightning, a bolt of lightning is hollow, and has no air inside it. When the lightning dissipates the air rushes to fill the space breaking the sound barrier in the process, this creates the boom.

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A high-jumper, having just cleared the bar, lands on an air mattress and comes to rest. Had she landed directly on the hard grou

Hoochie [10]

Answer:

e. the air mattress exerts the same impulse, but a smaller net avg force, on the high-jumper than hard-ground.

Explanation:

This is according to the Newton's second law and energy conservation that the force exerted by the hard-ground is more than the force exerted by the mattress.

The hard ground stops the moving mass by its sudden reaction in the opposite direction of impact force whereas the mattress takes a longer time to stop the motion of same mass in a longer time leading to lesser average reaction force.

Mathematical expression for the Newton's second law of motion is given as:

$F=\frac{dp}{dt}$ ............................................(1)

where:

dp = change in momentum

dt = time taken to change the momentum

We know, momentum:

$p=m.v$

Now, equation (1) becomes:

$F=\frac{d(m.v)}{dt}$

∵mass is constant at speeds v << c (speed of light)

$\therefore F=m.\frac{dv}{dt}$

and, $\frac{dv}{dt} =a$

where: a = acceleration

$\Rightarrow F=m.a$

also

$F\propto \frac{1}{dt}$

so, more the time, lesser the force.

& Impulse:

$I=F.dt$

$I=m.a.dt$

$I=m.\frac{dv}{dt}.dt$

$I=m.dv=dp$

∵Initial velocity and final velocity(=0), of a certain mass is same irrespective of the stopping method.

So, the impulse in both the cases will be same.

4 0

3 years ago

Which element has a magnetic properties

vodomira [7]

Answer:

Since then only three elements on the periodic table have been found to be ferromagnetic at room temperature - iron (Fe), cobalt (Co), and nickel (Ni). The rare earth element gadolinium (Gd) nearly misses by only 8 degrees Celsius.

Explanation:

3 0

3 years ago

Read 2 more answers

A massless rod is attached to the ceiling by a string. Two weights are hung from the rod: a 0.4-lb weight at its left end and a

user100 [1]

The tension in the string supporting the rod and the attached weights is 7.11 N.

<h3>Tension in the string supporting the rod</h3>

The tension in the string supporting the rod and the attached weights is the sum of the weights supported by the strings.

T = (m1 + m2)g

where;