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Tanya [424]
3 years ago
8

A 15kg object strikes the ground with 2000J of kinetic energy after freely falling from rest. How far above the ground was the o

bject when it was released?
Physics
1 answer:
arsen [322]3 years ago
8 0

Answer:

Explanation:

Find the final velocity at which it struck the ground by using the kinetic energy formula.

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

2000=\frac{1}{2} (15)v^2\\v=16.33

Now use kinematics to solve for the vertical displacement. We were given the initial velocity and acceleration can be assumed to be 9.8

V^2=V^2_i+2a(y_f-y_i)\\16.33^2=0^2+2(9.8)(y_f-y_i)

Δy = 13.6 meters

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A rope is tied to a box and used to pull the box 2.3 m along a horizontal floor. The rope makes an angle of 30∘ with the horizon
Savatey [412]

Answer:

Answered

Explanation:

A) The work done by gravity is zero because displacement and the gravitational force are perpendicular to each other.

W= FS cosθ

θ= 90 ⇒cos90 = 0 ⇒W= 0

B) work done by tension

W= Tcosθ×S= 5cos30×2.30= 10J

C) Work done by friction force

W= f×s=1×2.30= 2.30 J

D) Work done by normal force is Zero because the displacement and the normal force are perpendicular to each other.

E) The net work done= Work done by tension in the rope - frictional work

=10-2.30= 7.7 J

6 0
3 years ago
A ball is thrown vertically downwards with a speed 7.3 m/s from the top of a 51 m tall building. With what speed will it hit the
ddd [48]

Answer:

32.46m/s

Explanation:

Hello,

To solve this exercise we must be clear that the ball moves with constant acceleration with the value of gravity = 9.81m / S ^ 2

A body that moves with constant acceleration means that it moves in "a uniformly accelerated motion", which means that if the velocity is plotted with respect to time we will find a line and its slope will be the value of the acceleration, it determines how much it changes the speed with respect to time.

When performing a mathematical demonstration, it is found that the equations that define this movement are the follow

\frac {Vf^{2}-Vo^2}{2.a} =X

Where

Vf = final speed

Vo = Initial speed =7.3m/S

A = g=acceleration =9.81m/s^2

X = displacement =51m}

solving for Vf

Vf=\sqrt{Vo^2+2gX}\\Vf=\sqrt{7.3^2+2(9.81)(51)}=32.46m/s

the speed with the ball hits the ground is 32.46m/s

8 0
3 years ago
Read 2 more answers
In physics, power is __________.
Sedaia [141]

Answer:

The answer is A

Explanation:

4 0
2 years ago
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Use the equation PiVi PfVf. Assume that Pi 101 kPa and Vi 10.0 L. If Pf 43.0 kPa, what is Vf
iren2701 [21]
Solving for vf gives you PiVi/Pf. Now plug in 101kPa*10L/43kPa = 23.48L. Using significant figures i would round to 23.5L
8 0
3 years ago
So, like my previous question, how do you solve for 4/5 - 1/2?
ZanzabumX [31]

Answer:

3/10

Explanation:

4/5(2)

-1/2(5)

8/10-5/10

3/10

6 0
3 years ago
Read 2 more answers
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