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Yakvenalex [24]
4 years ago
14

An object is moving initially with a velocity of 4.7 m/s . After 3.9 s the object's velocity is -2.1 m/s . What is the object's

average acceleration during this time?
I believe that the vf is -2.1 m/s vi should be 4.7 m/s and the t should be 3.9s but its wrong..? #confused
Physics
1 answer:
IgorC [24]4 years ago
8 0

Answer: The acceleration of the object is 0.67m/s^2 west.

Explanation: Here we are given the initial velocity and final velocity as well as the time taken. Acceleration is the change in velocity per unit time, thus the equation becomes.

a=dv/t

a=vf-vi/t

a=-2.1-4.7/3.9

a= 0.66m/s^2 west

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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
What is the net force on this object f air = 400n (up) fgrav=600n (down)
n200080 [17]
Fnet=F1+F2 or Fnet=F1-F2
So 400n up - 600n down
Fnet= 400-600= -200N
5 0
3 years ago
Read 2 more answers
Winds tend to rotate in a counter clockwise direction in the ___ (northern or southern) Hemisphere as they move into a low press
lana [24]

Answer:

Winds tend to rotate in a counter clockwise direction in the center of northern and southern hemisphere.

Explanation:

The wind blows clockwise around a high pressure area  in the northern hemisphere and the wind blows counter - clockwise around low pressure.  

In the northern hemisphere High-pressure systems rotate clockwise direction and in the southern hemisphere  low-pressure systems rotate clockwise direction.

 

8 0
3 years ago
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"A boat that can travel at 4.0 km/h in still water crosses a river with a current of 2.0 km/h. At what angle must the boat be po
IRISSAK [1]

Answer:

30 degrees

Explanation:

8 0
3 years ago
If V has a magnitude of 14 units and the same direction qs a vector 3i+6j+2k find v​
melomori [17]

Answer:

v = 6i + 12j + 4k

Explanation:

Find the magnitude of the direction vector.

√(3² + 6² + 2²) = 7

Normalize the direction vector.

3/7 i + 6/7 j + 2/7 k

Multiply by the magnitude of v.

v = 14 (3/7 i + 6/7 j + 2/7 k)

v = 6i + 12j + 4k

7 0
3 years ago
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