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3 years ago

Which dog has the most kinetic energy?

Physics

2 answers:

Nadya [2.5K]3 years ago

5 0

A. A dog of mass 14kg running with the speed of 3m/s

Furkat [3]3 years ago

3 0

Nobody actually needs to know how much kinetic energy any of these dogs has.

The purpose of this question is to help you discover whether you know how to calculate kinetic energy, and then to give you some practice at doing it.

You have to calculate the kinetic energy of each dog, and then review your results to see which dog has the most.

The whole secret behind working this problem is the formula for the kinetic energy of any object:

Kinetic Energy = (1/2) · (mass) · (speed)²

The little ² next to 'speed' means 'squared' or 'multiplied by itself'.

(speed)² means (speed · speed) .

So, in order to calculate how much kinetic energy an object has, here's what you do:

-- Take the object's speed. Multiply the speed by itself.

-- Take that number and multiply it by the object's mass.

-- Take that number and throw away half of it.

So now here we go:

Dog A: KE = (1/2) (14 kg) (2 m/s)² = 28 Joules

Dog B: KE = (1/2) (14 kg) (3 m/s)² = 63 Joules

Dog C: KE = (1/2) (11 kg) (5 m/s)² = 137.5 Joules

Dog D: KE = (1/2) 12 kg) (4 m/s)² = 96 Joules

==> Dog C has more kinetic energy than any of the other 3 dogs.

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A beam of electrons moving in the x-direction enters a region where a uniform 208-G magnetic field points in the y-direction. Th

GREYUIT [131]

Answer:

$1.26\cdot 10^7 m/s$

Explanation:

When a charged particle moves perpendicularly to a magnetic field, the force it experiences is:

$F=qvB$

where

q is the charge

v is its velocity

B is the strength of the magnetic field

Moreover, the force acts in a direction perpendicular to the motion of the charge, so it acts as a centripetal force; therefore we can write:

$qvB=m\frac{v^2}{r}$

where

m is the mass of the particle

r is the radius of the orbit of the particle

The equation can be re-arranges as

$v=\frac{qBr}{m}$

where in this problem we have:

$q=1.6\cdot 10^{-19}C$ is the magnitude of the charge of the electron

$B=208 G=208\cdot 10^{-4}T$ is the strength of the magnetic field

The beam penetrates 3.45 mm into the field region: therefore, this is the radius of the orbit,

$r=3.45 mm = 3.45\cdot 10^{-3} m$

$m=9.11\cdot 10^{-31} kg$ is the mass of the electron

So, the electron's speed is

$v=\frac{(1.6\cdot 10^{-19})(208\cdot 10^{-4})(3.45\cdot 10^{-3})}{9.11\cdot 10^{-31}}=1.26\cdot 10^7 m/s$

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3 years ago

A 7.3 kg bowling ball would require how much force if you use a broom to

il63 [147K]

Answer:

0.219N

Explanation:

Given data

mass= 7.3kg

acceleration= 0.03m/s^2

We know that

F=ma

substitute

F= 7.3*0.03

F= 0.219N

Hence the applied force is 0.219N

7 0

3 years ago

A rope swing is hung from a tree right at the edge of a small creek. The rope is 5.0 m long; the creek is 3.0 m wide.

irina [24]

Answer:

1) T = 4.5 s

2) T = 4.5 s

3) v = 9.9 m/s

Explanation:

We can use the equation

T = 2π√(L/g)

1) T = 2π√(5m/9.81 m/s²) = 4.5 s

2) T = 2π√(L/g)

T = 2π√(5m/9.81 m/s²) = 4.5 s

3) v = √(2gR)

v = √(2(9.81 m/s²)(5m))

v = 9.9 m/s

8 0

4 years ago

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I stand 0.72 meters in front of a mirror and look at the person on the other side who looks like me. That person is actually you

Sergeu [11.5K]

Answer:

Younger by nanoseconds

Explanation:

Not entirely sure :O

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3 years ago

What energy transformation occurs when a skydiver first jumps from a plane

d1i1m1o1n [39]

The skydiver jumping from a plane high up in the sky would most likely experience various energy transformation. For starters, it would undergo a very large gravitational potential energy because of its much higher elevation. After jumping, this energy would eventually transform to kinetic energy due to the force exerted by the gravity.

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3 years ago

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