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2 years ago

If a rock weighing 2,200 N is dropped from a height of 15 m, what is its kenetic energy just before it hits the ground

Physics

1 answer:

ycow [4]2 years ago

7 0

Kinetic energy of the rock just before it hits the ground=KE=33000 J

Explanation:

Weight= 2200N

mg=2200

m(9.8)=2200

m=224.5 kg

initial velocity=0

final velocity =V

using kinematic equation V²=Vi²+2gh

V²=0+2 (9.8)(15)

V=17.1 m/s

now kinetic energy= 1/2 mV²

KE= 1/2 (224.5)(17.1)²

KE=33000 J

Thus the kinetic energy of the rock just before it hits the ground=33000 J

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In a game of pool, the cue ball strikes another ball of the same mass and initially at rest. After the collision, the cue ball m

ikadub [295]

(a) $-39.4^{\circ}$

Let's take the initial direction (before the collision) of the cue ball has positive x-direction.

Along the y-direction, the total initial momentum is zero:

$p_y =0$

Therefore, since the total momentum must be conserved, it must be zero also after the collision. So we write:

$0 = m v_1 sin \phi_1 + m v_2 sin \phi_2 \\0 = m(4.60) sin (28^{\circ}) + m(3.40) sin \phi_2$

where

m is the mass of each ball

$v_1= 4.60 m/s$ is the velocity of the cue ball after the collision

$v_2 = 3.40 m/s$ is the velocity of the second ball after the collision

$\phi_1=28.0^{\circ}$ is the angle of the cue ball with the x-axis

$\phi_2$ is the angle of the second ball

Solving for $\phi_2$ , we find the angle between the direction of motion of the second ball and the original direction of motion:

$sin \phi_2 = -\frac{4.60 sin 28}{3.40}=-0.635\\\phi_2 = -39.4^{\circ}$

(b) 6.69 m/s

To find the original speed of the cue ball, we analyze the situation along the horizontal direction.

First, we calculate the total momentum along the x-direction after the collision, which is:

$p_x = m v_1 cos \phi_1 + m v_2 cos \phi_2 \\0 = m(4.60) cos (28^{\circ}) + m(3.40) cos (-39.4^{\circ})=6.69 m$

The initial total momentum along the x-direction as

$p_x = m u$

where

m is the mass of the cue ball

$u$ is the initial velocity of the cue ball

The momentum along this direction must be conserved, so we can equate the two expressions and find the value of u:

$mu = 6.69 m\\u = 6.69 m/s$

7 0

3 years ago

I NEED HELP ASAP!! I NEED IT BEFORE TOMORROW!! D: 10pts+5pts!

Wewaii [24]

9. Compounds can form from two nonmetals by sharing their electrons in a
C) covalent

11. An atom that has an excess positive or negative electrical charge caused by the loss or addition of an electron is called a(n) ______.
B) ion

5 is either A or C

4 0

2 years ago

One complete expression of a waveform beginning at a certain point, progressing through the zero line to the wave’s highest (cre

elixir [45]

Answer:

wavelength.

Explanation:

One complete expression of a waveform beginning at a certain point, progressing through the zero line to the wave’s highest (crest) and lowest (trough) points, and returning to the same value as the starting point is called a is called wavelength. Its can be also defined as the distance between two successive crests or trough points in wave form.

4 0

2 years ago

Which type of sedimentary rock is formed from rock and mineral fragments weathered from rocks at earth’s surface?

Zanzabum

Answer:

The correct answer is detritic rocks.

Explanation:

Sedimentary rocks are rocks formed by the accumulation of sediments, particles of various sizes that are transported by water, ice or wind, which are subjected to physical and chemical processes, resulting in consolidated materials.

Sedimentary rocks formed from the accumulation of mineral deposits and rocks from erosion and deposited by gravity are called detritic rocks.

Have a nice day!

6 0

2 years ago

Consider a box weight 2700 newtons resting on the ground. If the area of the box touching the ground is 1.5 square meters, what

Neko [114]

Answer:

The answer to your question is 1800 Pa

Explanation:

Data

Weight = 2700 N

Area = 1.5 m²

Pressure = ?

Formula

Pressure = Force / Area

The Pressure is defined as the force exerted per unit area.

-Substitution

Pressure = 2700 / 1.5

-Result

Pressure = 1800 Pa

The units of pressure are Pascals (Pa)

6 0

2 years ago