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4 years ago

Which is a result of using a machine?

2 answers:

6 0

D.
The energy into the system is the same as that out of the system. Its just that a small force is applied over a larger distance at one end while a large force is applied over a smaller distance at the other end. Keep in mind:
Work = Force x displacement
The work remains constant.

liraira [26]4 years ago

4 0

The correct answer is:

D. A large force can be exerted through a short distance to have a small force exerted through a long distance.

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#2 A car accelerates from rest at 4 m/s^2. What is the velocity of the car after 4 second?

solmaris [256]

You use the equation Velocity = Acceleration X Time. 4x4=16m/s.

The car travels 18m in 3 seconds.

3 0

4 years ago

I need to know the answer

Phoenix [80]

i think number 1 is D number 2 is B

4 0

3 years ago

Need help as fast as possible please Thank you!

alekssr [168]

Answer:

b is the answer.. hope it helps

5 0

3 years ago

Read 2 more answers

A copper transmission cable 140 {\rm km} long and 12.5 {\rm cm} in diameter carries a current of 115 {\rm A}.

SpyIntel [72]

Answer:

1. $V=22.0407\ V$

2. $Q=9126837\ J$

Explanation:

Given:

length of copper cable, $l=140\ km=1.4\times 10^5\ m$

diameter of copper cable, $d=12.5\ cm=0.125\ m$

current through the copper wire, $i=115\ A$

We have the resistivity of copper, $\rho=1.68\times10^{-8}\ \Omega.m$

We know that the resistance of a wire is given as:

$R=\rho.\frac{l}{a}$

where:

$a=$ cross sectional area of the wire

$R=1.68\times 10^{-8}\times\frac{140000}{\pi.\frac{0.125^2}{4} }$

$R=0.1917\ \Omega$

Now from the Ohm's law:

$V=R.i$

$V=0.1917\times 115$

$V=22.0407\ V$

From the Joules law the thermal energy generated as an effect of electrical energy is mathematically given as:

$Q=i^2.R.t$

where:

$t=$ time duration for which the current flows

$Q=115^2\times 0.1917\times 3600$ (∵ we have 3600 seconds in 1 hour)

$Q=9126837\ J$

5 0

3 years ago

A model rocket blasts off and moves upward with an acceleration of 12 m/s2 until it reaches a height of 26 m. at that height, it

Diano4ka-milaya [45]

initial acceleration of rocket is given as

a = 12 m/s^2

h = 26 m

now we can use kinematics to find its speed

$v_f^2 - v_i^2 = 2 a h$

$v_f^2 - 0 = 2 * 12*26$

$v_f = 24.98 m/s$

now after this it will be under free fall

so now again using kinematics

$v_f = 0$

at maximum height

$v_f^2 - v_i^2 = 2 a s$

$0 - 24.98^2 = 2 * (-9.8)* h$

$h = 31.8 m$

total height from the ground = 31.8 + 26 = 57.8 m

Part b)

now after reaching highest height it will fall to ground

So in order to find the speed we can use kinematics again

$v_f^2 - v_i^2 = 2 a d$

$v_f^2 - 0 = 2*9.8*57.8$

$v_f = 33.67 m/s$

Part c)

first rocket accelerate to reach height 26 meter and speed becomes 24.98 m/s

now we have

$v_f - v_i = a t$

$24.98 - 0 = 12*t_1$

$t_1 = 2.1 s$

after this it will reach to highest point and final speed becomes zero

$v_f - v_i = at$

$0 - 24.98 = -9.8 * t$

$t_2 = 2.55 s$

now from this it will fall back to ground and reach to final speed 33.67 m/s

now we have

$v_f - v_i = at$

$33.67 - 0 = 9.8 * t$

$t_3 = 3.44 s$

so total time is given as

t = 3.44 + 2.55 + 2.1 = 8.1 s

5 0

3 years ago