What is the kinetic energy of a 30 kg falling object when the object reaches a velocity of 20 m/s?

Answers

Answer 1

Answer: Ek = 1/2mv^2 Ek = 1/2 * 30kg * 20^2 m/s Ek = 6000J Hope this Helps!

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A ball is projected horizontally from the top of a 92.0-meter high cliff with an initial speed of 19.8 m/s. Determine: (a) the horizontal displacement and (b) the final speed the instant prior to hitting the ground.

Answers

Answer:

Part a)

$d = 85.8 m$

Part b)

$v = 46.8 m/s$

Explanation:

Part a)

As we know that ball is projected horizontally

so here the vertical speed of the ball is zero

now we have

$y = (1)/(2)gt^2$

now we have

$92 = (1)/(2)(9.8)t^2$

$t = 4.33 s$

now in the same time the horizontal distance covered by the ball

$d = v_x t$

$d = 19.8 * 4.33$

$d = 85.8 m$

Part b)

now the horizontal speed of the ball always remains constant

so we have

$v_x = 19.8 m/s$

now in vertical direction we have

$v_y = v_0 + at$

$v_y = 0 + 9.8(4.33)$

$v_y = 42.4 m/s$

so the final speed of the ball is given as

$v = √(v_y^2 + v_x^2)$

$v = √(42.4^2 + 19.8^2)$

$v = 46.8 m/s$

The ball has two independent motions; the vertical motion and the horizontal motion.
That is the ball is falling vertically downwards from the cliff and the same time the ball is moving horizontally forward from the cliff.
Note: Initial Vertical Speed is = 0, Initial Horizontal Speed = 19.8 m/s
For the vertical motion: the initial velocity is zero. That is $u_(y)$ = 0.
S = ( $u_(y)$ )t + (1/2)gt^2. where g = acceleration due to gravity = 10 m/s^2
S = Vertical height = 92m
Substituting $u_(y)$ = 0, and S = 92m, g = 10m/s^2
92 = 0*t + (1/2)*10*t^2
92 = (1/2)*10*t^2
92 = 5t^2
5t^2 = 92
t^2 = 92/5
t^2 = 18.4 Take square root of both sides
t = $√(18.4)$
t = 4.29 seconds, that is the time to reach the ground. Time is same both for horizontal and vertical motion

a) Horizontal Displacement, which is Range R = Horizontal Speed * time
R = $u_(x)$ * time
R = 19.8 * 4.29 = 84.942 m.

b) Final Speed before hitting the ground.
Remember we realized that speed was in two parts: Vertical Speed and Horizontal Speed.
Just before hitting the ground Horizontal speed is same = 19.8 m/s, this is the same as the initial horizontal projected speed. (No acceleration in Horizontal direction so this remains the same)
Just before hitting the ground, $v_(y) = u_(y) + gt$
At projection Vertical speed is initially zero  $u_(y) = 0$
$v_(y) = 0 + 10*4.29$
Time is same both for horizontal and vertical motion
$v_(y)$ = 42.9 m/s
The velocity just before hitting the ground is 19.8 m/s in the horizontal direction and 42.9 m/s in the vertical direction.
These two are at right angles to each other. Therefore the resultant is:
= $\sqrt{19.8^(2)+ 42.9^(2) }$
= 47.25 m/s.
This is the resultant velocity just before it hits the ground.

A monkey is sitting on a tree when it sees a hunter claiming a near by tree. The Hunter is aiming directly at the head of the monkey.The money jumps out of the tree at the exact same time the arrow is released from the hunters bow.

Assume the Hunter has perfect aim, the monkey has zero reaction time and that air resistance is negligible.

Explain wether the monkey will avoid bring struck by the arrow.

Answers

yes as the speed or velocity of gun's bullet is very higher than the monkey so struck by the arrow

a bullet of mass m is fired into a block of mass m that is at rest. the block, with the bullet embedded, slides distance d across a horizontal surface. the coefficient of kinetic friction is μk.

Answers

The expression for the bullet's speed vbullet is $v=\sqrt{(2\mu_k (m+M)gd)/(m)}$ and the speed of a 9.0 g bullet is v=16.8 m/s

Explanation:

A bullet of mass m is fired into a block of mass m that is at rest. the block, with the bullet embedded, slides distance d across a horizontal surface. the coefficient of kinetic friction is μk.

The initial kinetic energy of the bullet is given by

$K_i = (1)/(2)mv^2$

where

m is the mass of the bullet

v is the initial speed of the bullet

The expression for the bullet's speed vbullet is

$F=\mu_k (m+M) g$

where

$\mu_k$ is the coefficient of kinetic friction

g is the acceleration of gravity

The work done by the force of friction is

$W=-Fd = -\mu_k (m+M)g d$

where d is the displacement of the block+bullet.

Because the final kinetic energy is zero (the bullet with the block comes at rest), we can write:

$W=K_f - K_i = -K_i$

And so

$-\mu_k (m+M) g d = -(1)/(2)mv^2$

By solving for v, the solution for the bullet speed:

$-\mu_k (m+M) g d = -(1)/(2)mv^2\nv=\sqrt{(2\mu_k (m+M)gd)/(m)}$

The speed of a 9.0 g bullet that, when fired into a 12 kg stationary wood block causes the block to slide 5.4 cm across a wood table. Assume that k=0.20.

We have:

the mass of the bullet, m = 9.0 g = 0.009 kg

the mass of the block, M = 12 kg

the distance covered by the block+bullet, d = 5.4 cm = 0.054 m

the coefficient of friction, $\mu_k = 0.20$

the acceleration of gravity, $g = 9.8 m/s^2$

By substituting, we got

$v=\sqrt{(2 (0.20) (0.009 kg+12 kg)(9.8 m/s^2)(0.054 m))/(0.009 kg)}=16.8 m/s$

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uk=2m*the normal force
the distance d is needed only if you were asked about work

What force results in charged particles?A] Contact Force

B] Gravitational Force

C] The Force Of Electromagnetism

D] Force Push

Answers

B gravitational forces

Answer:

The Force Of Electromagnetism

Explanation:

hope this helps u

How is pressure measured?a. Pressure is measured as force per inch
b. Pressure is measured as force per gram
c. Pressure is measured as force per unit area
d. Pressure is measured as force divided by mass
I think its D...

Answers

Answer: The correct answer is " Pressure is measured as force per unit area".

Explanation:

Pressure is defined as the force per unit area.

The expression for the pressure is as follows:

$P=(F)/(A)$

Here, F is the applied force and A is the area.

The pressure is inversely proportional to the area. More the area, lesser will be the pressure. Lesser the area, more will be pressure.

For example, the area of the strap of the school bag is more so that there will be less pressure on the students's shoulder.

Therefore, the correct option is (c).

Pressured is measured by the Force per unit area

Most of the Earth's volcanoes occurA.
near the center of tectonic plates.
B.
where there are no tectonic plates.
C.
along tectonic plate boundaries.
D.
before tectonic plates can form.

Answers

Answer: C. along tectonic plate boundaries

Explanation:

Right on Study Island 2021

Answer:

Explanation:

NEAR THE CENTER OF TECTONIC PLATES.

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