Answer:
4.5%
Explanation:
efficiency = energy out / energy in
e = 9.3×10⁴ J / 2.06×10⁶ J
e = 0.045
I would say unlimited polarity because the compass’s needle is always attracted to Earth’s north pole.
Good luck to you!
Answer:
70 kg is the mass of the object
Explanation:
This question can be solved with this simple formula:
Weight force = mass . gravity
686 N = mass . 9.8 m/s²
686 N / 9.8 m/s² = mass → 70 kg
Note → 1N = 1 kg . m / s²
The Newton’s law Nikolas would use to come up with this idea is the <span>Third law that states:
</span><span>When one body exerts a force on a second body, the second body simultaneously exerts a force equal in magnitude and opposite in direction on the first body.
</span>
So, in this case, let's name the first Body
A which is the skateboard and the second body
B which is <span>the compressed carbon dioxide in a fire extinguisher. Then, as shown in the figure below, according to the Third law:
</span>

<span>
</span>
Given
Weight of the block A, Wa = 20 lb, weight of block B Wb = 50 lb. Applied
force to block A, P = 6lb, coefficient of static friction µs = 0.4, coefficient
of kinetic friction µk = 0.3. If a force P
is applied to the body, no relative motion will take place until the applied
force is equal to the force of friction Ff, which is acting opposite to the
direction of motion. Magnitude of static force of friction between block A and
block B, Fs = µsN, where N is
reaction force acting on block A. Now, resolve the forces Fx = max. P = (mA +
mB)a,
6 = (20 / 32.2 + 50 / 32.2)a
2.173a = 6
A = 2.76 ft/s^2
To check slipping occurs between block A and block B, consider block A:
P – Ff = mAaA
6 – Ff = 1.71
Ff = 4.29 lb
And also,
N = wA. We know static friction,
Fs = µsN
Fs = 0.4 x 20
Fs = 8lb
Frictional force is less than static friction. Ff < Fs
<span>Therefors, acceleration of block A, aA = 2.76 ft/s^2, acceleration of
block B aB = 2.76 ft/s^2</span>