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Amanda [17]
3 years ago
12

Why is it important to know the direction of the force applied to a moving object and the direction in which the object is movin

g when determining the work done on the object?
A. Only the component of the force perpendicular to the motion is used to calculate the work.

B. If the force acts in the same direction as the motion, then no work is done.

C. When there is an angle between the two directions, the cosine of the angle must be considered.

D. A force at a right angle to the motion requires the use of the sine of the angle.
Physics
1 answer:
ELEN [110]3 years ago
3 0
C is correct.  The work-force relation is given by W=F·d, where F is force vector, and d is the displacement vector.  The dot is the dot product, which is a measure of how parallel the two vectors are.  It can be restated as the product of two vector magnitudes times the cosine of the angle between them.  Therefore work is a scalar, not a vector, since the dot product returns a scalar.  
W=Fdcos(\theta)
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zysi [14]

Answer:

x(t) = -8sin2t

Explanation:

See the attachment for solution

From my solving, we can deduce that w² = 4, and thus, w = 2

Therefore, the general solution is

x(t) = c1 cos2t + c2 sin2t

Considering the final variable, we can conclude that

x(0) = 0

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4 0
2 years ago
In the same configuration of the previous problem 3, four long straight wires are perpendicular to the page, and their cross sec
faust18 [17]

Complete Question:

In the same configuration of the previous problem 3, four long straight wires are perpendicular to the page, and their cross sections form a square of edge length a = 13.5 cm. Each wire carries 7.50 A, and the currents are out of the page in wires 1 and 4 and into the page in wires 2 and 3.

a) Draw a diagram in a (x,y) plane of the four wires with wire 4 perpendicular to the origin. Indicate the current's directions.

b) Draw a diagram of all magnetic fields produced at the position of wire 3 by the other three currents.

c) Draw a diagram of all magnetic forces produced at the position of wire 3 by the other three currents.

d) What are magnitude and direction of the net magnetic force per meter of wire length on wire 3?

Answer:

force, 1.318 ₓ 10⁻⁴

direction, 18.435°

Explanation:

The attached file gives a breakdown step by step solution to the questions

7 0
3 years ago
Certain rifles can fire a bullet with a speed of 950 m/s just as it leaves the muzzle (this speed is called the muzzle velocity)
TiliK225 [7]

Answer:

a) By v^2 = u^2 + 2as => a= 70291.70.

(b)By v = u + at => t= 1.58 ms.

(c)By v^2 = u^2 - 2gh => H = 46045.92 m.

Explanation:

a) By v^2 = u^2 + 2as

(950)^2 = 0 + 2 \times a \times 0.75\\a = 601666.67 m/s^2\\a/g = 688858.70/9.8 = 70291.70

(b)By v = u + at

950 = 0 + 601666.67 \times t\\t = 1.58 x 10^-3 sec = 1.58 ms

(c)By v^2 = u^2 - 2gh

0 = (950)^2 - 2 \times9.8 \times H\\H = 46045.92 m

4 0
2 years ago
Which of the following is true about plants and cellular energy?
kkurt [141]

Answer:

D

Explanation:

6CO² + 6H²O > sunlight, chlorophyll, enzymes > C⁶H¹²O⁶ + 6O²

3 0
3 years ago
When did robert fulton invent the steamboat
bekas [8.4K]

Answer:

1807

Explanation:

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7 0
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