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makkiz [27]
3 years ago
7

You do a certain amount of work on an object initially at rest, and all the work goes into increasing the object’s speed. If you

do work WITH, suppose the object’s final speed is v. What will be the object’s final speed if you do twice as much work?1. 4 v2. 2 v3. still v4. v/25. v.2
Physics
1 answer:
mezya [45]3 years ago
7 0

Answer:

v_{f2} = √ 2 v_{f}

Explanation:

Work and kinetic energy are related by

       W = ΔK

The formula for work is

    W = F . d

The formula for kinetic energy is

      K = ½ m v²

     W = K_{f} - K₀

Since the body starts from rest, the initial velocity is ro and therefore the kinetic energy is zero.

       W = K_{f}

       W = ½ m v_{f}²

       v_{f} = √ 2W / m

       

    If  W = 2 W₀

       v_{f2} = √ 2 (2W₀) / m

       v_{f2} = √ 2  √2W₀ / m

       v_{f2} = √ 2 v_{f}

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padilas [110]

Answer: T= 715 N

Explanation:

The only external force (neglecting gravity) acting on the swinging mass, is the centripetal force, which. in this case, is represented by the tension in the string, so we can say:

T = mv² / r

At the moment that the mass be released, it wil continue moving in a straight line at the same tangential speed that it had just an instant before, which is the same speed included in the centripetal force expression.

So the kinetic energy will be the following:

K = 1/2 m v² = 15. 0 J

Solving for v², and replacing in the expression for T:

T = 1.9 Kg (3.97)² m²/s² / 0.042 m = 715 N

3 0
3 years ago
How many position coordinates are required to identify the position of a system undergoing one-dimensional motion? What symbol s
gregori [183]
One-dimensional motion can be plotted through the Cartesian plane which has a coordinates of (x,y). These coordinates are the abscissa and ordinates. Since, there are two coordinates, the answer to the second item is two.

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6 0
3 years ago
Why does a gymnast rub powder on his hands before exercising on a set of parallel bars? (I need a scientific answer)
dlinn [17]

<u>Answer</u>

To increase friction for a better grip.

<u>Answer</u>

Most human beings do sweat hands especially on the palm. When this happens the person will not have a good grip of heavy objects because they will slide/slip from the hand.

<em>By applying the powder, you are trying to make the hand dry hence increasing the friction for a better grip. </em>

If the gymnast doesn't do this the parallel bars may slip from the hands and injure himself or herself.

4 0
3 years ago
Read 2 more answers
A railroad freight car of mass 3.34 × 104 kg collides with a stationary caboose car. They couple together, and 19.0% of the init
Tresset [83]

Answer:

4.123 * 10∧4 kg

Explanation:

mass of car M' = 3.34 * 10∧4 kg

energy loss E = 19/100  K

from law of conservation of momentum ,

                 M' V' = ( M' + M'' ) v

                        V = M' V' / ( M' + M'' )

       Initial kinetic energy is K'  = (M' V')² / 2

      final kinetic energy  K" = 81 K' /100

                                             =  (M' V')² 81 / (200)     =   ( M' + M'' ) v²/ 2

            therefore , M' / ( M' + M" ) = 0.81

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                                          = 0,234 ( 3.34 * 10∧4 kg)

                                          = 4.123 * 10∧4 kg

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3 years ago
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Marrrta [24]
Part A: a->positive when velocity is increasing a->negative when velocity is decreasing a->zero when velocity is constant
6 0
3 years ago
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