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ludmilkaskok [199]

3 years ago

10

Georgie was pulling her brother (of mass 16 kg) in a 9.4 kg sled with a constant force of 39 N for one block (128 m). How much w

ork did Georgie do? Answer in units of J.

1 answer:

Genrish500 [490]3 years ago

7 0

Answer:

4992 J

Explanation:

Force, F = 39 N

Distance, s = 128 m

Work done = force x distance

W = 39 x 128

W = 4992 J

Thus, the work done is 4992 J.

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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.

6 0

3 years ago

The power in an electrical circuit is given by the equation P= RR, where /is

Rainbow [258]

Answer:D

Explanation:Electric power=I*I*R

=12*12*100

=14400watts

6 0

3 years ago

One hazard of space travel is the debris left by previous missions. There are several thousand objects orbiting Earth that are l

MariettaO [177]

Answer:

F = 6666.7 N

Explanation:

Given that,

Mass of a chip, m = 0.1 mg

Initial speed, u = 0

Final speed, $v=4\times 10^{3}\ m/s$

Time of collision, $t=6\times 10^{-8}\ s$

We know that,

Force, F = ma

Put all the values,

$F=\dfrac{m(v-u)}{t}\\\\F=\dfrac{0.1\times 10^{-6}\times (4\times 10^3-0)}{6\times 10^{-8}}\\\\F=6666.7\ N$

So, the required force is 6666.7 N.

3 0

3 years ago

An isolated conducting sphere has a 10 cm radius. One wire carries a current of 1.000 002 0 A into it. Another wire carries a cu

romanna [79]

Answer:

t = 5.56 ms

Explanation:

Given:-

- The current carried in, Iin = 1.000002 C

- The current carried out, Iout = 1.00000 C

- The radius of sphere, r = 10 cm

Find:-

How long would it take for the sphere to increase in potential by 1000 V?

Solution:-

- The net charge held by the isolated conducting sphere after (t) seconds would be:

qnet = (Iin - Iout)*t

qnet = t*(1.000002 - 1.00000) = 0.000002*t

- The Volt potential on the surface of the conducting sphere according to Coulomb's Law derived result is given by:

V = k*qnet / r

Where, k = 8.99*10^9 ..... Coulomb's constant

qnet = V*r / k

t = 1000*0.1 / (8.99*10^9 * 0.000002)

t = 5.56 ms

7 0

3 years ago

What is the charge of an atom that has lost one electron?

Luden [163]

Answer:

positive

An atom has a even amount of protons, electrons, and a little less neutrons. If the atom lost one electron, then it now has a positive charge.

Hope it helps!

5 0

3 years ago