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Mila [183]
3 years ago
12

An 80 kg skateboarder moving at 3 m/s pushes off with her back foot to move faster. If her velocity increases to 5 m/s, what is

her change in kinetic energy as a result? J How much work did she perform? J
Physics
1 answer:
Serga [27]3 years ago
3 0

Answer:

640 J

Explanation:

ΔKE = KE − KE₀

ΔKE = ½ mv² − ½ mv₀²

ΔKE = ½ m (v² − v₀²)

ΔKE = ½ (80 kg) ((5 m/s)² − (3 m/s)²)

ΔKE = 640 J

Her kinetic energy increases by 640 J, so she does 640 J of work.

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A 25-kg child sits at the top of a 4-meter slide. After sliding down, the child is traveling at 5 m/s. How much PE does he start
Semmy [17]

Daniddmelo says it right there, don't know why he got reported.

The potential energy (PE) is mass x height x gravity. So it would be 25 kg x 4  m x 9.8 = 980 joules. The child starts out with 980 joules of potential energy. The kinetic energy (KE) is (1/2) x mass x velocity squared. KE = (1/2) x 25 kg x 5 m/s2 = 312.5 joules. So he ends with 312.5 joules of kinetic energy. The Energy lost to friction =  PE - KE. 980- 312.5 = 667.5 joules of energy lost to friction.

Please don't just copy and paste, and thank you Dan cause you practically did it I just... elaborated more? I dunno. 

4 0
3 years ago
In which city did the wright brothers take off on their very first flight
Nezavi [6.7K]
<h2>Answer: Kitty Hawk, North Carolina </h2>

The Wright brothers, Wilbur and Orville, were pioneers of aviation, since they flew in a device heavier than air, which was inconceivable at that time.

Their first successful flight was on December 17th, 1903 in Kitty Hawk, North Carolina, which lasted only 12 seconds in which their plane (the Flyer I, with 341 kg, 6.4 m long and a wingspan of 12.3 m) traveled 37 m without touching the ground. This was achieved through the help of an external catapult that "threw" them into the air.

It should be noted that the Wright brothers only studied until high school, however, their passion for solving the problem of the human inability to fly, their perseverance and experience acquired over the years in their bicycle company, led them to reach that goal. An achievement that marked the beginning of the  aviation era.

7 0
3 years ago
A truck loaded with sand accelerates along a highway. The driving force on the truck remains constant. What happens to the accel
pickupchik [31]

Answer:

Acceleration will increase.

Explanation:

The relation between force, mass and acceleration according to the Newton's second law of motion is given as:

F = ma

We are given that the driving force on the truck remains constant, so F is constant here. We can rewrite the above equation as:

a=\frac{F}{m}

Since, F is constant, the acceleration of the truck is inversely proportional to the mass.

There is a hole at the bottom of the truck through which the sand is being lost at a constant rate. Since, the sand is being lost, the overall mass of the truck is being reduced.

Since, the acceleration of the truck is inversely proportional to the mass, the reduced mass will result in an increased acceleration.

So, the acceleration of the truck will increase.

4 0
3 years ago
How does a fuse work?
Vilka [71]

Answer:

A. a material burns out when current is excessive

5 0
3 years ago
Is is false or true The closer objects are, the stronger the gravitational force between them.
____ [38]

Answer:

<em>TRUE</em>

Explanation:

The gravitational force between two objects becomes<u><em> weaker</em></u><em> if the two objects are </em><u><em>moved apart</em></u> and <em>stronger</em><em> if they are brought </em><em>closer</em><em> together</em>; that is, the force depends on the distance between the objects

5 0
3 years ago
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