(a) Differentiate the position vector to get the velocity vector:
<em>r</em><em>(t)</em> = (3.00 m/s) <em>t</em> <em>i</em> - (4.00 m/s²) <em>t</em>² <em>j</em> + (2.00 m) <em>k</em>
<em>v</em><em>(t)</em> = d<em>r</em>/d<em>t</em> = (3.00 m/s) <em>i</em> - (8.00 m/s²) <em>t</em> <em>j</em>
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(b) The velocity at <em>t</em> = 2.00 s is
<em>v</em> (2.00 s) = (3.00 m/s) <em>i</em> - (16.0 m/s) <em>j</em>
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(c) Compute the electron's position at <em>t</em> = 2.00 s:
<em>r</em> (2.00 s) = (6.00 m) <em>i</em> - (16.0 m) <em>j</em> + (2.00 m) <em>k</em>
The electron's distance from the origin at <em>t</em> = 2.00 is the magnitude of this vector:
||<em>r</em> (2.00 s)|| = √((6.00 m)² + (-16.0 m)² + (2.00 m)²) = 2 √74 m ≈ 17.2 m
(d) In the <em>x</em>-<em>y</em> plane, the velocity vector at <em>t</em> = 2.00 s makes an angle <em>θ</em> with the positive <em>x</em>-axis such that
tan(<em>θ</em>) = (-16.0 m/s) / (3.00 m/s) ==> <em>θ</em> ≈ -79.4º
or an angle of about 360º + <em>θ</em> ≈ 281º in the counter-clockwise direction.
Answer:
C. The net work done by the two forces is zero joules.
Explanation:
Work (W) is defined as the product of force F) by the distance (d)the body travels due to this force.
W= F*d Formula ( 1)
The work is positive (W+) if the force has the same direction of movement of the object.
The work is negative (W-) if the force has the opposite direction of the movement of the object.
The component of the force that performs work must be parallel to the displacement.
Calculation of the forces
We apply Newton's second law:
∑F = m*a
∑F : algebraic sum of the forces in Newton (N)
m : mass in kilograms (kg)
a : acceleration in meters over second square (m/s²)
∑F = m*a
a = 0 because the elevator moves at constant speed.
∑F=0
T-W = 0
T = W
Calculation of work done by the forces
W₁ : work done by the gravity= (+ W*d ) J
W₂ : work done by the tension force=( -T*d) J
Net work done by the two forces(W₁-W₂):
W₁= W₂ .because T = W
W₁-W₂ =0
Answer:
Your answer would be C, Radio waves.
Explanation:
The first one would be thermal energy
Answer:
a soft foam material because soft materials absorb sound better
