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vredina [299]
3 years ago
13

A 45.0 kg skater is skating at a speed of 12.0 m/s. The skater coasts to a speed of 6.00 m/s. How much kinetic energy has the sk

ater lost?
Physics
1 answer:
ratelena [41]3 years ago
6 0
Kinetic energy is the energy of an object that is moving. It is calculated from one-half the product of the mass and the change in square of the velocity of the object. It is the opposite of potential energy which the energy possessed by an object at rest. We calculate as follows:
KE = mΔv^2 / 2 = 45 ( 6^2 - 12^2 ) = -4860 J had been lost by the skater
You might be interested in
How long does it take an object to travel 375 m at a rate of 25 m/s?
Leni [432]

Answer:

15s

Explanation:

Given parameters:

Distance traveled  = 375m

Speed = 25m/s

Unknown:

Time taken = ?

Solution:

To solve this problem, we make time the subject of the speed equation.

    Speed  = \frac{distance}{time}  

  Time  = \frac{distance}{speed}  

 Now insert the parameters and solve;

  Time  = \frac{375}{25}   = 15s

3 0
3 years ago
Two astronauts push on a satellite. One pushes in the positive x direction with a force of 42 N, and the other pushes in the pos
inessss [21]

The vectors adition we can find the magnitude of the force applied by the other astronaut is  11.25 N in the y direction

 

Parameters given

  • Force of an astronaut Fₓ = 42 N
  • Angle θ = 15º

To find

  • Force another astronaut

The force is a vector magnitude for which the addition of vectors must be used, a very efficient method to perform this sum is to add the components of each vector and devise constructing the resulting vector using trigonometry and the Pythagorean theorem.

Let's use trigonometry to find the other force

            tan θ = \frac{F_y}{F_x}

            F_ y = Fₓ tan θ

let's calculate

            F_y = 42 tan 15

            F_y = 11.25 N

Using the summation of vectors we can find the magnitude of the force applied by the other astronaut is 11.25 N in the y direction

Learn more about vector addition here:

brainly.com/question/15074838

4 0
3 years ago
Since the aluminum bar is not an isolated system, the second law of thermodynamics cannot be applied to the bar alone. Rather, i
max2010maxim [7]

Answer:

ΔS total ≥ 0 (ΔS total = 0 if the process is carried out reversibly in the surroundings)

Explanation:

Assuming that the entropy change in the aluminium bar is due to heat exchange with the surroundings ( the lake) , then the entropy change of the aluminium bar is, according to the second law of thermodynamics, :

ΔS al ≥ ∫dQ/T

if the heat transfer is carried out reversibly

ΔS al =∫dQ/T  

in the surroundings

ΔS surr ≥ -∫dQ/T = -ΔS al → ΔS surr ≥ -ΔS al = - (-1238 J/K) = 1238 J/K

the total entropy change will be

ΔS total = ΔS al + ΔS surr

ΔS total ≥ ΔS al + (-ΔS al) =

ΔS total ≥ 0

the total entropy change will be ΔS total = 0 if the process is carried out reversibly in the surroundings

4 0
4 years ago
6. A car moving in a straight line at constant speed:
ddd [48]

Answer:

D. has no overall force acting on it.

Explanation:

Why?

Because in a straight line at the constant speed means the car moving in the same velocity, which is not acceleration neither deceleration, and it cannot be on a downhill slope. So the correct answer is

<h3>→ D. has no overall force acting on it.</h3>
8 0
3 years ago
In one of the original Doppler experiments, a tuba was played at a frequency of 64.0 Hz on a moving flat train car, and a second
wolverine [178]

Answer:

 f_{beat} = 1.64\ Hz

Explanation:

given,

frequency of tuba.f = 64 Hz

Speed of train approaching, v = 8.50 m/s

beat frequency = ?

using Doppler's effect formula

 f' = f(\dfrac{v}{v-v_s})

v_s is the velocity of the source

v is the speed of sound, v = 340 m/s

now,

 f' = 64\times (\dfrac{340}{340 - 8.50})

       f' = 65.64 Hz

now, beat frequency is equal to

 f_{beat} = f' - f

 f_{beat} = 65.64 - 64

 f_{beat} = 1.64\ Hz

hence, beat frequency is equal to 1.64 Hz

3 0
3 years ago
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