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3 years ago

2. Two trailers, X with mass 500 kg and Y with mass 2000 kg, are being pulled at the same

Physics

1 answer:

leva [86]3 years ago

4 0

Answer:C

Explanation:

let the speed be v for both mass x and mass y

mass(x)=500kg

mass(y)=2000kg

Kinetic energy(mass(x))=(500 x v^2)/2

Kinetic energy(mass(x))=250v^2

Kinetic energy(mass(y))=(2000xv^2)/2

Kinetic energy(mass(y))=1000v^2

Ratio of kinetic energy y to x =1000v^2:250v^2

=1000v^2 / 250v^2

=4/1=4:1

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A ray of light strikes the midpoint of one face of an equiangular crown glass prism (n=1.52) at an angle of incidence of 30.0.

NikAS [45]

Answer:

Angle of reflection at plane surface of prism = 30°

Explanation:

Angle of reflection = angle of incidence at any surface plane or curved .

Here angle of incidence at plane surface of prism = 30°

Angle of reflection at plane surface of prism = 30°

If i be the angle of incidence and r be angle of refraction

sin i / sin r = refractive index

= 1.52

sin r = sin i / 1.52

= sin 30 / 1.52

= .5 / 1.52

= .3289

r = 19.2 °

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3 years ago

A block with mass ma = 14.0 kg on a smooth horizontal surface is connected by a thin cord that passes over a pulley to a second

Drupady [299]

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4 years ago

Earth changes all the time making it a __ planet.

seraphim [82]

The answer is Dynamic.

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3 years ago

Read 2 more answers

Please help me with 1&2

Oxana [17]

Answer:

1: A

Explanation:

7 0

3 years ago

A large boulder is ejected vertically upward from a volcano with an initial speed of 40.0 m/s. Ignore air resistance. (a) At wha

dezoksy [38]

a) Time at which velocity is +20.0 m/s: 2.04 s

b) Time at which velocity is -20.0 m/s: 6.12 s

c) Time at which the displacement is zero: t = 0 and t = 8.16 s

d) Time at which the velocity is zero: t = 4.08 s

e) i) ii) iii) The acceleration of the boulder is always $9.8 m/s^2$ downward

f) See graphs in attachment

Explanation:

The motion of the boulder is a uniformly accelerated motion, with constant acceleration

$a=g=-9.8 m/s^2$

downward (acceleration due to gravity). So, we can use the following suvat equation:

$v=u+at$

where:

v is the velocity at time t

u = 40.0 m/s is the initial velocity

a=g=-9.8 m/s^2 is the acceleration

We want to find the time t at which the velocity is

v = 20.0 m/s

Therefore,

$t=\frac{v-u}{a}=\frac{20-40}{-9.8}=2.04 s$

In this case, we want to find the time t at which the boulder is moving at 20.0 m/s downward, so when

v = -20.0 m/s

(the negative sign means downward)

We use again the suvat equation

$v=u+at$

And substituting

u = +40.0 m/s

a=g=-9.8 m/s^2

We find the corresponding time t:

$t=\frac{v-u}{a}=\frac{-20-(+40)}{-9.8}=6.12 s$

To solve this part, we can use the following suvat equation:

$s=ut+\frac{1}{2}at^2$

where

s is the displacement

u = +40.0 m/s is the initial velocity

$a=g=-9.8 m/s^2$ is the acceleration

t is the time

We want to find the time t at which the displacement is zero, so when

s = 0

SUbstituting into the equation and solving for t,

$0=ut+\frac{1}{2}at^2\\t(u+\frac{1}{2}a)=0$

which gives two solutions:

t = 0 (initial instant)

$u+\frac{1}{2}at=0\\t=-\frac{2u}{a}=-\frac{2(40)}{-9.8}=8.16 s$

which is the instant at which the boulder passes again through the initial position, but moving downward.

To solve this part, we can use again the suvat equation

$v=u+at$

where

u = +40.0 m/s is the initial velocity

$a=g=-9.8 m/s^2$ is the acceleration

We want to find the time t at which the velocity is zero, so when

v = 0

Substituting and solving for t, we find:

$t=\frac{v-u}{a}=\frac{0-(40)}{-9.8}=4.08 s$

In order to evaluate the acceleration of the boulder, let's consider the forces acting on it.

If we neglect air resistance, there is only one force acting on the boulder: the force of gravity, acting downward, with magnitude

$F=mg$

where m is the mass of the boulder and $g$ the acceleration of gravity.

According to Newton's second law, the net force on the boulder is equal to the product between its mass and its acceleration:

$F=ma$

Combining the two equations, we get

$ma=mg\\a=g$

So, the acceleration of the boulder is $g=9.8 m/s^2$ downward at any point of the motion, no matter where the boulder is (because the force of gravity is constant during the motion).

Find the three graphs in attachment:

- Position-time graph: the position of the boulder initially increases as the boulder goes upward; however, the slope of the curve decreases as the boulder goes higher (because the velocity decreases). The boulder reaches its maximum height at t = 4.08 s (when velocity is zero), then it starts going downward, until reaching its initial position at t = 8.16 s

- Velocity-time graph: the initial velocity is +40 m/s; then it decreases linearly (because the acceleration is constant), and becomes zero when t = 4.08 s. Then the velocity becomes negative (because the boulder is now moving downward) and its magnitude increases.

- Acceleration-time graph: the acceleration is constant and it is $-9.8 m/s^2$ , so this graph is a straight horizontal line.

Learn more about accelerated motion:

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3 years ago