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2 years ago

In which of the following examples does the object have both kinetic and potential energy? Select all that apply.

Physics

1 answer:

Andru [333]2 years ago

8 0

Objects having both kinetic and potential energy:

water flowing downstream

a child swinging on a swing

a bouncing ball

a plane in flight at 30,000 feet

Explanation:

The kinetic energy of an object is the energy possessed by the object due to its motion. It is given by

$KE=\frac{1}{2}mv^2$

where

m is the mass of the object

v is its speed

Therefore, an object has kinetic energy when its speed is non-zero (so, whenever it is moving).

The potential energy of an object is the energy possessed by the object due to its position in the gravitational field. It is given by

$PE=mgh$

where

m is the mass

g is the acceleration of gravity

h is the heigth of the object relative to the ground

Therefore, an object has potential energy whenever it is located at a certain height above the ground.

So in this problem, the objects that have both kinetic and potential energy are:

a rock at the edge of a cliff --> NO, because the rock is at rest (so KE = 0)

water flowing downstream --> YES, because the water is moving AND it is at a certain height above the ground

a child swinging on a swing --> YES, because the child is moving AND it is at a certain height above the ground

a bouncing ball --> YES, because the ball is moving AND it is at a certain height above the ground

water behind a dam --> NO, because the water is at rest (so KE=0)

a car moving on a level road --> NO, because the car is at ground level (so PE=0)

a plane in flight at 30,000 feet --> YES, because the plane is moving AND it is at a certain height above the ground

a compressed spring --> NO, because the spring is at rest (so KE=0)

Learn more about kinetic and potential energy:

brainly.com/question/6536722

brainly.com/question/1198647

brainly.com/question/10770261

#LearnwithBrainly

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2 years ago

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Answer:

Q=1005 J

t= 0.67 sec

Explanation:

Lets take condition of room is 1 atm and 25°C.

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2 years ago

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Ans:
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Explanation:

The figure is attached down below.

1. T<span>orque about the elbow caused by the biceps, τbiceps:
Since Torque = r x F (where r and F are the vectors)
</span>Where r is the vector from elbow to the biceps.
<span>
We can see in the figure that F(biceps) is in upward direction, and by applying the right hand rule from r to F, we get the counterclockwise direction. The torque in counterclockwise direction is positive(+). Therefore, the sign would be +.

2. </span>Torque about the the weight of the forearm, τforearm:
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