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4 years ago

What is the formula for calculating kinetic energy?

Physics

2 answers:

svetoff [14.1K]4 years ago

8 0

Explanation :

An object is moving with initial velocity of u and its final velocity is v. If it covers a distance s moving with an acceleration a. So, the relation between them is :

$v^2-u^2=2as$

So, $s=\dfrac{v^2-u^2}{2a}$ ...............(1)

If a force (F = m a) is applied to it then the work is done by it. It is given as :

$W=m\times a\times s$

$W=ma\times \dfrac{v^2-u^2}{2a}$

$W=\dfrac{1}{2}m(v^2-u^2)$

If u = 0

then, $W=\dfrac{1}{2}mv^2$

From work energy theorem, the work done is equal to the change in kinetic energy.

$E_k=\dfrac{1}{2}mv^2$

The kinetic energy is possessed due to the motion of an object.

Hence, this is the required solution.

aniked [119]4 years ago

5 0

Kinetic energy is the energy possessed by an object having some mass and moving at some speed due to its motion. Kinetic energy is given as

KE = (0.5) m v²

where KE = kinetic energy

m = mass of the object in motion

v = speed of the object in motion.

it is a scalar quantity and has only magnitude and no direction.

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AysviL [449]

Answer:

C and E...................

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3 years ago

Squids and octopuses propel themselves by expelling water. They do this by keeping water in a cavity and then suddenly contracti

Zigmanuir [339]

Answer:

10.1 m/s

Explanation:

By Newton's third law, the force on the squid and that due to the water expelled form an action reaction pair.

And by the law of conservation of momentum,

initial momentum of squid + expelled water = final momentum of squid + expelled water.

Now, the initial momentum of the system is zero.

So, 0 = final momentum of squid + expelled water

0 = MV + mv where M = mass of squid = 6.50kg, V = velocity of squid = 2.40m/s, m =mass of water in cavity = 1.55 kg and v = velocity of water expelled

So, MV + mv = 0

MV = -mv

v = -MV/m

= -6.50 kg × 2.40 m/s ÷ 1.55 kg

= -15.6 kgm/s ÷ 1.55 kg

= -10.1 m/s

So, speed must it expel this water to instantaneously achieve a speed of 2.40 m/s to escape the predator is 10.1 m/s

4 0

3 years ago

as you take a short canoe trip on the Brazos River you paddle your canoe 200 miles up the river in 420 seconds and then turn aro

Maurinko [17]

200 miles/420 secs = 10/21
350 mile/280 secs = 5/4

(5/4+10/21)/2= 145/168 miles per sec
or .86 miles/sec

8 0

3 years ago

The flywheel of a steam engine runs with a constant angular velocity of 150 rev/min. When steam is shut off, the friction of the

Annette [7]

Answer:

a) $\ddot n = -1.563\,\frac{rev}{min^{2}}$ , b) $\Delta n = 7197.697\,rev$ , c) $a_{t} = 1.009\times 10^{-3}\,\frac{m}{s^{2}}$ , d) $a = 22.823\,\frac{m}{s^{2}}$

Explanation:

a) Constant angular acceleration is:

$\ddot n = \frac{\dot n - \dot n_{o}}{\Delta t}$

$\ddot n = \frac{0\,\frac{rev}{min} - 150\,\frac{rev}{min}}{(1.6\,h)\cdot \left(60\,\frac{min}{h} \right)}$

$\ddot n = -1.563\,\frac{rev}{min^{2}}$

b) The amount of revolutions required to stop the flywheel is:

$\Delta n = \frac{\dot n^{2}-\dot n_{o}^{2}}{2\cdot \ddot n}$

$\Delta n = \frac{\left(0\,\frac{rev}{min} \right)^{2}-\left(150\,\frac{rev}{min} \right)^{2}}{2\cdot \left(-1.563\,\frac{rev}{min^{2}} \right)}$

$\Delta n = 7197.697\,rev$

c) The tangential acceleration of the particle is:

$a_{t} = \left(1.563\,\frac{rev}{min^{2}} \right)\cdot \left(\frac{1}{3600}\,\frac{min^{2}}{s^{2}}\right)\cdot \left(2\pi\,\frac{rad}{rev}\right)\cdot (0.37\,m)$

$a_{t} = 1.009\times 10^{-3}\,\frac{m}{s^{2}}$

d) The radial acceleration of the particle is:

$a_{r} = \left[\left(75\,\frac{rev}{min} \right)\cdot \left(\frac{1}{60}\,\frac{min}{s} \right)\cdot \left(2\pi\,\frac{rad}{rev} \right)\right]^{2}\cdot (0.37\,m)$

$a_{r} = 22.823\,\frac{m}{s}$

The net linear acceleration is:

$a = \sqrt{a_{r}^{2}+a_{t}^{2}}$

$a = \sqrt{\left(22.823\,\frac{m}{s^{2}} \right)^{2}+\left(1.009\times 10^{-3}\,\frac{m}{s^{2}} \right)^{2}}$

$a = 22.823\,\frac{m}{s^{2}}$

3 0

3 years ago

In which of the following is radiation the only type of heat transfer?

horrorfan [7]

Answer:

C.Vacuum

Explanation:

There are three methods of transfer of heat:

1) Conduction: conduction is the transfer of heat by direct contact between the molecules of two objects (or two substances). The particles of the hotter object vibrate faster than the particles of the colder object, so energy is transferred by collisions of the molecules from the hotter object to the colder object.

2) Convection: convection is the transfer of heat by mass movement of molecules. This occurs in fluids (liquids or gases), when an external source of heat is applied to the fluid. As a result, the part of the fluid closer to the source gets warmer, so it becomes less dense and rises, while the colder part sinks and replaces the hotter part, forming a convective current. The process continues until the heat source is removed.

3) Radiation: radiation is the transfer of heat carried by electromagnetic waves. Electromagnetic waves can travel in any medium and in a vacuum, so they are the only type of heat transfer that can occur in a vacuum (while conduction and convection cannot occur in a vacuum).

8 0

3 years ago

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