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3 years ago

Define the fundamental difference between kinematics and dynamics. .

1 answer:

5 0

In kynematics you describe the motion of particles using vectors and their change in time. You define a position vector r for a particle, and then define velocity v and acceleration a as

$v=\frac{dr}{dt} \\$

$a=\frac{dv}{dt}$

In dynamics Newton's laws predict the acceleration for a given force. Knowing the acceleration, and the kynematical relations defines above, you can solve for the position as a function of time: r(t)

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Light rays in a material with index of refraction 1.31 can undergo total internal reflection when they strike the interface with

3241004551 [841]

Answer:

The refractive index of the material is 1.28.

Explanation:

It is given that,

Refractive index of medium 1, n₁ = 1.31

Critical angle, $\theta_c=78.3$

At critical angle rays will reflects at 90 degrees. Using Snell's law as:

$n_1sin\theta_1=n_2sin\theta_2$

At critical angle, $n_1sin\ \theta_c=n_2\ sin90$

$n_1sin\ \theta_c=n_2$

$n_2=1.31\times sin(78.3)$

$n_2=1.28$

So, the refractive index of the material is 1.28. Hence, this is the required solution.

3 0

3 years ago

If a ball is thrown up at an initial speed of 40. m/s, how many seconds does it take to reach the top of its path?

natka813 [3]

Answer:

Time, t = 4.08 secs

Explanation:

Given the following data;

Initial velocity, U = 40m/s

To find the time, we would use the first equation of motion;

$V = U + at$

Where;

V is the final velocity.

U is the initial velocity.

a is the acceleration.

t is the time measured in seconds.

Making time, t the subject of formula, we have;

$t = \frac{V - U}{a}$

We know that acceleration due to gravity, g is 9.8m/s².

a = g = - 9.8m/s² because the ball is thrown in the opposite direction.

Also, the final velocity is equal to zero (0) because the ball reached its maximum height.

Substituting into the equation, we have;

$t = \frac{0 - 40}{-9.8}$

$t = \frac{-40}{-9.8}$

Time, t = 4.08 secs

Therefore, it will take the ball 4.08 seconds to reach the top.

5 0

3 years ago

While riding a chairlift, a 55-kilogram skier is raised a vertical distance of 370 meters. What is the total change in the skier

Lelechka [254]

The change in the skier's gravitational potential energy is 199430 J.

<h3> Gravitational potential energy:</h3>

This is the energy of a body due to its position in a gravitational field. The S.I unit of gravitational potential energy is Joules (J)

The Change in the skier's gravitational potential energy can be calculated using the formula below.

Formula:

ΔP.E = mg(Δh)............... Equation 1

Where:

ΔP.E = Change in the skier's potential energy
m = mass of the skier
Δh = change in height to which it was raised
g = acceleration due to gravity.

From the question,

Given:

m = 55 kg
Δh = 370 m

g = 9.8 m/s²

Substitute these values into equation 1

ΔP.E = 55×370×9.8
ΔP.E = 199430 J.

Hence, The change in the skier's gravitational potential energy is 199430 J.

Learn more about potential energy here: brainly.com/question/1242059

3 0

2 years ago

Tin shear have longer handles than than the scissor used to cut cloth give reason

natka813 [3]

Answer:

For scissor, small movement at effort(at handle) should make long movement of load arm , so that it can cut longer lengths of cloth/paper. Hence blades are longer than handle.so its handle(load arm) is made longer than its blades.

Explanation:

Hope this helped Mark BRAINLEST!!

8 0

3 years ago

You stand at the top of a deep well. To determine the depth, D, of the well you drop a rock from the top of the well and listen

Paladinen [302]

Answer:

(A)

$\displaystyle D^2-\left (\frac{2v_s^2}{g}+2t_tv_s \right )D+t_t^2v_s^2=0$

(B) D=54.71 m

Explanation:

Free Fall

When a particle is dropped in free air, it starts falling to the ground with an acceleration equal to the gravity. If one wanted to know the height of launching, it can indirectly be measured by the time it takes to reach the ground by the formula

$\displaystyle D=\frac{gt^2}{2}$

Solving for t

$\displaystyle t=\sqrt{\frac{2D}{g}}$

If we are taking into consideration the time we can hear the sound it makes when hitting the ground (or water in this case), we must also consider the speed of the sound for the time it takes to reach back our ears. That time can be computed from the basic equation for the speed

$\displaystyle t=\frac{D}{v_s}$

(A)

The total measured time is the sum of both times and it's given as $t_t=3.5\ seconds$

$\displaystyle t_t=\sqrt{\frac{2D}{g}}+\frac{D}{v_s}$

From this equation we'll manage to compute D

First, we isolate the square root

$\displaystyle \sqrt{\frac{2D}{g}}=t_t-\frac{D}{v_s}$

Let's square both sides

$\displaystyle \frac{2D}{g}=t_t^2-2t_t\frac{D}{v_s}+\frac{D^2}{v_s^2}$

Multiplying by $v_s^2$

$\displaystyle \frac{2Dv_s^2}{g}=t_t^2v_s^2-2t_tDv_s+D^2$

Rearranging and factoring

$\boxed{\displaystyle D^2-\left (\frac{2v_s^2}{g}+2t_tv_s\right )D+t_t^2v_s^2=0}$

Now, let's put in numbers:

$g=9.8\ m/s^2,\ v_s=345\ m/s,t_t=3.5\ sec$

$\displaystyle D^2-\left (\frac{2(345)^2}{9.8}+2(3.5)(345)\right )D+(12.25)345^2=0$

Computing all the coefficients:

$\displaystyle D^2-26,705.82D+1,458,056.25=0$

Solving for D, we have two possible solutions:

$D=54.71,\ D=26,651.11$

The second solution is called "extraneous", since it comes from squaring an equation, which can introduce non-valid (or external) solutions. It's impossible, given the conditions of the problem, that the well could be 26.5 km deep. So we'll keep the only solution as.

D=54.71 m

Let's prove our calculations by computing both times:

$\displaystyle t_1=\sqrt{\frac{2(54.71)}{9.8}}=3.34\ sec$

$\displaystyle t_2=\frac{54.71}{345}=0.16\ sec$

We can see their sum is 3.5 seconds, 3.34 of which were taken to reach the bottom of the well, and 0.16 sec took the sound to reach the top.

3 0

3 years ago