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2 years ago

Ball 1 is thrown to the ground with an initial downward speed; ball 2 is dropped to the ground from rest.

Physics

1 answer:

MariettaO [177]2 years ago

8 0

Answer:

equal to the change in gravitational potential energy of ball 2.

Explanation:

Change in gravitational potential energy is equal to work done by gravitational force on the body .

work done = force x displacement

force = mg

displacement = height ( h )

change in gravitational energy = mgh

Since mass is same in both the cases , g is also the same in both the cases and h too is same in both the cases . change in gravitational energy will be same in both the cases. Initial velocity will have no affect on the result at all.

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A 4.5 kg box slides down a 4.3-m-high frictionless hill, starting from rest, across a 2.0-m-wide horizontal surface, then hits a

Rainbow [258]

Answer:

speed before reaching rough surface = 9.18 m/s

speed before hitting spring = 8.70 m/s

spring compression = 82 cm

number of complete trip = 9

Explanation:

Lets say

Position 1: On top of hill

Position 2: down the hill

Position 3: after the rough surface

Position 4: after hitting the spring

We'll strictly use conservation of energy for this equation

Potential energy on top of energy is full converted into kinetic energy down the hill (since surface is frictionless)

Hence, PEg1 = KE2

mgh = (1/2)mv2^2

(4.5)(9.8)(4.3) = (1/2)(4.5)v2^2

189.63 = (1/2)(4.5)v2^2

v2^2 = 2(9.8)(4.3) = 84.28

v2 = sqrt(84.28) = 9.18 m/s

After down the hill, it passes a rough surface. So some of the energy is loss due to friction forces

Friction force, Ff = u (coeff of kinetic friction ) x N (normal force)

Normal force, N = weight of box = mg = 4.5 x 9.8

Ff = 0.22 x 4.5 x 9.8

Work done / Energy loss = Wf = Ff x d (distance)

Wf = 0.22 x 4.5 x 9.8 x 2 = 19.404

Energy after passing the rough surface is totally kinetic energy

KE3 = KE2 - Wf = 189.63 - 19.404 = 170.226

speed after rough surface,

(1/2)mv3^2 = 170.226

v3 = sqrt((2 x 170.226)/4.5) = 8.70 m/s

After hitting the spring, all the kinetic energy is converted into potential energy of spring

170.226 = (1/2)kx^2

x^2 = 2 x 170.226 / 510 {note that constant of spring, k = 510}

x^2 = 0.668

x = sqrt(0.668) = 0.82m (82 cm)

To calculate complete trip before the box coming to rest, note that the only place where it loss energy is at the rough surface.

Energy before the first time pass rough surface = 189.63

Energy loss each time passing rough surface = 19.404

189.63 / 19.404 = 9.773 (9 complete with balance of 0.773)

That mean, the box will pass the rough surface 9 complete trip before coming to rest

8 0

3 years ago

B. A car moving at an initial speed vi applies its brakes and skids for some distance until coming to a complete stop. If the co

wariber [46]

Complete Question

The complete question is shown on the first uploaded image

Answer:

The distance which the car skid is $l = \frac{v_i^2 }{2 * \mu_k * g }$

Explanation:

From the question we are told that

The initial velocity of the car is $v_i$

The coefficient of kinetic friction is $\mu_k$

According to the law of energy conservation

The initial Mechanical Energy = The final Mechanical Energy

$M_i = M_f$

The initial mechanical energy is mathematically represented as

$M_i = KE _o + PE_e$

where KE is the initial kinetic energy which is mathematically represented as

$KE = \frac{1}{2} m v_i^2$

And PE is the initial potential energy which is zero given that the car is on the ground

Now

$M_f = W_{\mu}$

Where $W_{\mu}$ is the work which friction exerted on the car which is mathematically represented as

$W_{\mu} = m* \mu_k * g * l$

Where $l$ is the distance covered by the car before it slowed down

$\frac{1}{2} m v_i^2 = m* \mu_k * g * l$

=> $l = \frac{v_i^2 }{2 * \mu_k * g }$

3 0

3 years ago

When does it start to cool down in arizona?

KatRina [158]

<span>It starts to cool down in Arizona in mid-October. The weather remains good in October- April and the heat tends to break in mid of October. The time when it is coldest in Arizona in December or January. However, it's too hot in the month of July and Rain becomes common in Spring season.</span>

7 0

3 years ago

What words does convection come from

ludmilkaskok [199]

Answer:

from Late Latin convectionem

Explanation:

6 0

2 years ago

A young child is playing with a very flexible hose. She is moving her hand back and forth making transverse type waves. She move

aev [14]

Answer:

The waves will increase in frequency

Explanation:

As the young girl moves her hand back and forth faster, it will be observed that number of back and forth motions increase every second. Also the distance between crest and trough of the wave (wavelength) will be reduced as she moves her hand back and forth faster.

Frequency = number of turns (moves) per second

The waves will increase in frequency since there will be more number of back and forth motions in every second.

Also,

The distance between crest and trough will be reduced, which implies that there will be decrease in waves wavelength.

This can also be verified using wave equation;

V = Fλ

At constant velocity,

F ∝ ¹/λ

Thus, decrease in wavelength will cause increase in frequency of the waves.

The right answer is : The waves will increase in frequency

5 0

3 years ago