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3 years ago

14

Struggling with this. Can you help?

1 answer:

pishuonlain [190]3 years ago

6 0

Answer:

Unclear without more information

Explanation:

This is about transfer of energy. If you assume there is no energy lost to the environment (virtually impossible) - then all of the potential energy at the beginning would be transferred to kinetic energy along the route.

So, assuming that the rollercoaster has a velocity of 0 m/s at point A, then you can calculate the potential energy using: $Ep =mgh_A$

At the point D, you would assume that the energy is split between some kinetic energy and some potential energy. So, we could say that the total energy is the sum of these: $Etot=Ep+Ek=mgh_{D} +\frac{mv^2}{2}$

If we assume all energy is transferred (ie. no energy lost to friction/heat etc) then we can equate these two and solve:

$mgh_A=mgh_{D} +\frac{mv^2}{2}\\\\h_D=\frac{(2gh_A-v^2)}{2g} =22.4$

However, this answer seems unlikely given the drawing - which implies that there is perhaps more information that is missing??

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when in object moves stop moving changes speed or changes direction how do scientist describe that condition?

Kruka [31]

im taking test rn nd this question was on there, im saying unbalanced force, if it not correct i will put right answer, but im pretty sure the answer is unblanced

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3 years ago

Read 2 more answers

A car initially at rest accelerates at 10m/s^2. The car’s speed after it has traveled 25 meters is most nearly... A.) 0.0m/s B.)

STALIN [3.7K]

The car traverses a distance $x$ after time $t$ according to

$x=\dfrac12at^2$

where $a$ is its acceleration, 10 m/s^2. The time it takes for the car to travel 25 m is

$25\,\mathrm m=\left(5\dfrac{\rm m}{\mathrm s^2}\right)t^2\implies t=\sqrt 5\,\mathrm s$

5 is pretty close to 4, so we can approximate the square root of 5 by 2. Then the car's velocity $v$ after 2 s of travel is given by

$v=\left(10\dfrac{\rm m}{\mathrm s^2}\right)(2\,\mathrm s)\approx20\dfrac{\rm m}{\rm s}$

which makes C the most likely answer.

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3 years ago

Coil the wire around the nail. Connect one end of the wire to the positive battery terminal. Connect the other end of the wire t

Andrej [43]

Static i think
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3 years ago

A cord is used to vertically lower an initially stationary block of mass M = 3.6 kg at a constant downward acceleration of g/7.

dalvyx [7]

Answer:

(a) $W_c=127.008 J$

(b) $W_g=148.176 J$

(c) K.E. = 21.168 J

(d) $v=3.4293m.s^{-1}$

Explanation:

Given:

mass of a block, M = 3.6 kg

initial velocity of the block, $u=0 m.s^{-1}$

constant downward acceleration, $a_d= \frac{g}{7}$

$\Rightarrow$ That a constant upward acceleration of $\frac{6g}{7}$ is applied in the presence of gravity.

∴ $a=- \frac{6g}{7}$

height through which the block falls, d = 4.2 m

(a)

Force by the cord on the block,

$F_c= M\times a$

$F_c=3.6\times (-6)\times\frac{9.8}{7}$

$F_c=-30.24 N$

∴Work by the cord on the block,

$W_c= F_c\times d$

$W_c= -30.24\times 4.2$

We take -ve sign because the direction of force and the displacement are opposite to each other.

$W_c=-127.008 J$

(b)

Force on the block due to gravity:

$F_g= M.g$

∵the gravity is naturally a constant and we cannot change it

$F_g=3.6\times 9.8$

$F_g=35.28 N$

∴Work by the gravity on the block,

$W_g=F_g\times d$

$W_g=35.28\times 4.2$

$W_g=148.176 J$

(c)

Kinetic energy of the block will be equal to the net work done i.e. sum of the two works.

mathematically:

$K.E.= W_g+W_c$

$K.E.=148.176-127.008$

K.E. = 21.168 J

(d)

From the equation of motion:

$v^2=u^2+2a_d\times d$

putting the respective values:

$v=\sqrt{0^2+2\times \frac{9.8}{7}\times 4.2 }$

$v=3.4293m.s^{-1}$ is the speed when the block has fallen 4.2 meters.

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3 years ago

The periodic table lists all the elements according to the number of __________ they have! You can’t change __________ without c

raketka [301]

Answer:

protons

atomic number

Note: The same atomic number can be associated with several different values of atomic mass, but an element can have only 1 atomic number,

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2 years ago