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dsp73
3 years ago
11

A 4 kg bowling ball rolls at a speed of 5 m/s on the roof of a building that is 30 meters tall. What is its kinetic energy?

Physics
1 answer:
klasskru [66]3 years ago
3 0

ans: B

Kinetic energy = \frac{1}{2} mv^{2}

= \frac{1}{2} (4)(5^{2} )

= 50J

ps. the height will only affect its potential energy, not kinetic.

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A 1090 kg car moving +11.0 m/s
stiks02 [169]

The mass of the second car is 1434.21 kg

<u>Explanation:</u>

Using law of conservation of momentum,

          m_{1} u_{1}+m_{2} u_{2}=\left(m_{1}+m_{2}\right) v

Given:

m_{1} = 1090 kg

u_{1} = 11 m/s

u_{2} = 0

v = 4.75 m/s

We need to find m_{2}

When substituting the given values in the above equation, we get

(1090 \times 11)+\left(m_{2} \times 0\right)=\left(1090+m_{2}\right) 4.75

11990=5177.5+4.75 m_{2}

4.75 m_{2}=11990-5177.5

4.75 m_{2}=6812.5

m_{2}=\frac{6812.5}{4.75}=1434.21 \mathrm{kg}

6 0
2 years ago
A boy is playing with a ball of mass 72g attached to a string. He is moving it at constant speed in a horizontal circle of radiu
irina [24]

Answer:

Explanation:

radius of circle r = 0.9 m.

(a ) In a motion on circular path , work done is zero because force ( centripetal force ) acts perpendicular to displacement .

( b )

Tension in string T = m ω²r

Putting the values

60 = .072 x ω² x 0.9

ω² = 926

ω = 30.4 rad /s

angle made in 20 revolutions θ = 20 x 2π = 126.6 rad

time taken = θ / ω

= 126.6 / 30.4

= 4.16 s .

3 0
3 years ago
A 0.547 kg pizza is thrown straight up in the air. At a height of 2.30 m above the surface of the earth it has a speed of 5.00 m
natima [27]

Answer:

The total mechanical energy of the pizza crust is 19.2 J.

Explanation:

Mechanical energy is that which a body or a system obtains as a result of the speed of its movement or its specific position, and which is capable of producing mechanical work. Then:

Potential energy + kinetic energy = total mechanical energy

Kinetic energy is a form of energy. It is defined as the energy associated with bodies that are in motion and this energy depends on the mass and speed of the body.

Kinetic energy is defined as the amount of work necessary to accelerate a body of a certain mass and in a position of rest, until it reaches a certain speed.

Kinetic energy is represented by the following formula:

Ec = ½ *m*v²

Where Ec is kinetic energy, which is measured in Joules (J), m is mass measured in kilograms (kg), and v is velocity measured in meters over seconds (m / s).

In this case:

  • m=0.547 kg
  • v= 5 m/s

Replacing:

Ec = ½ *0.547 kg*(5 m/s)²

and solving you get:

Ec= 6.8375 J

On the other hand, potential energy is the energy that measures the ability of a system to perform work based on its position. In other words, this is the energy that a body has at a certain height above the ground.

Gravitational potential energy is the energy associated with the gravitational force. This will depend on the relative height of an object to some reference point, the mass, and the force of gravity. Then for an object with mass m, at height h, the expression applied to the gravitational energy of the object is:

Ep = m*g*h

Where Ep is the potential energy in joules (J), m is the mass in kilograms (kg) is h the height in meters (m) and g is the acceleration of fall in m / s² (approximately 9.81 m/s²)

In this case:

  • m= 0.547 kg
  • g= 9.81 m/s²
  • h= 2.30 m

Replacing

Ep= 0.547 kg *9.81 m/s²* 2.30 m

and solving you get:

Ep= 12.342 J

So:

Total mechanical energy= 12.342 J + 6.8375 J

Total mechanical energy= 19.1795 J≅ 19.2 J

<u><em>The total mechanical energy of the pizza crust is 19.2 J.</em></u>

6 0
3 years ago
Which of the following statements is true?
Lilit [14]

A. All natural radiation is at a level low enough to be safe

8 0
3 years ago
One of the largest planes ever to fly, and the largest to fly frequently, is the Ukrainian-built Antonov An-124 Ruslan. The grav
Lerok [7]

Answer:

m = 236212 [kg]

Explanation:

The potential energy can be determined by means of the product of mass by gravity by height. In this way, we have the following equation.

P=m*g*h\\

where:

P = potential energy = 3360000000 [J]

m = mass [kg]

g = gravity acceleration = 9.81 [m/s²]

h = elevation = 1450 [m]

Now, we can clear the mass from the equation above:

3360000000=m*9.81*1450\\m = 236212 [kg]

4 0
3 years ago
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