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2 years ago

Show that the expression vf = vi + at is dimensionally correct

1 answer:

4 0

To show that the expression given is dimensionally correct, we can do a dimensional analysis where we write the units of each term in the expression.

vf [=] vi + at
m/s [=] m/s+ (m/s²) (s)
<span>m/s [=] m/s+ m/s
</span><span>m/s [=] m/s
</span>
Therefore, the expression is dimensionally correct.

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An electric device, which heats water by immersing a resistance wire in the water, generates 50 cal of heat per second when an e

Oksi-84 [34.3K]

Answer:

0.69 ohm

Explanation:

Heat generated per second, H = 50 cal/s

Potential difference, V = 12 V

Let R is the resistance of coil.

The formula for the heat is given by

$H = \frac{V^{2}}{R}t$

$50\times 4.186 = \frac{12^{2}}{R}\times 1$

R = 0.69 ohm

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2 years ago

Car A hits car B (initially at rest and of equal mass) frombehind while going 35 m/s. Immediately after the collision, car Bmove

kolezko [41]

Answer:

The fraction of kinetic energy lost in the collision in term of the initial energy is 0.49.

Explanation:

As the final and initial velocities are known it is possible then the kinetic energy is possible to calculate for each instant.

By definition, the kinetic energy is:

k = 0.5*mV^2

Expressing the initial and final kinetic energy for cars A and B:

$ki=0.5*maVa_{i}^2+0.5*mbVb_{i}^2$

$kf=0.5*maVa_{f}^2+0.5*mbVb_{f}^2$

Since the masses are equals:

$m=ma=mb$

For the known velocities, the kinetics energies result:

$ki=0.5*mVa_{i}^2$

$ki=0.5*m(35 m/s)^2=612.5m^2/s^2*m$

$kf=0.5*mbVb_{f}^2$

$kf=0.5*m(25 m/s)^2=312.5m^2/s^2*m$

The lost energy in the collision is the difference between the initial and final kinectic energies:

$kl=ki-kf$

$kl = 612.5m^2/s^2*m-312.5 m^2/s^2*m=300 m^2/s^2*m$

Finally the relation between the lost and the initial kinetic energy:

$kl/ki = 300 m^2/s^2 * m / 612.5 m^2/s^2 * m$

$kl/ki = 24/49=0.49$

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2 years ago

Calculate the impulse imparted when a 3,000-kg car hits a wall at 60 . m/s and comes to a stop.

Pani-rosa [81]

Impulse = change in momentum

The answer is 0.

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2 years ago

A student hangs a wood block from a spring. The student pulls the block downwards so the spring is stretched and holds the block

Murrr4er [49]

Kinetic energy because of the wood plank is just still and not moving it’s potential but since it’s asking which one it doesn’t have it doesn’t have kinetic energy cause it’s not moving

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2 years ago

Which is the largest gas that occurs in our atmosphere?

Mademuasel [1]

Answer:

OXYGEN

Explanation:brainlyist me

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2 years ago

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