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astraxan [27]
3 years ago
14

The normal force acting on an object and the force of static friction do zero work on the object. However the reason that the wo

rk is zero is different for the two cases. Explain why each does zero work.
Physics
1 answer:
spin [16.1K]3 years ago
3 0

Answer:

<em>The normal force is perpendicular to the displacement</em>

<em>The static friction force produces no displacement</em>

Explanation:

Work Done By Special Forces

The work is a physical magnitude that measures the dot product of the force applied to an object by the displacement it produces in it.

W=\vec F\ \vec r

It can be written in its scalar version as

W=F.d.cos\theta

Being F and d the magnitudes of the force and displacement, and \theta the angle between them

If the angle is zero, the work is at maximum, it the angle is 90°, the work is zero. If the angle is between 90° and 180°, the work is negative.

The normal force acts in the vertical direction when the object is being pushed horizontally. It means the angle between the force and the displacement is 90°, thus the work is

W=N.d.cos90^o=0

The work is zero because the force and the displacement are perpendicular

The static friction force exists only when the object is being applied a force of a magnitude not large enough to produce movement, i.e. the object is at rest. If the object is moved, the friction force is still present, but it's called dynamic friction force, usually smaller than the static.

Since in this case, there is no displacement, d=0, and the work is

W=F_r(0)cos180^o=0

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3 years ago
The whale shark is the largest of all fish and can have the mass of three adult
ch4aika [34]

Answer:

m = 20,000 kg

Explanation:

Force, F=2.5\times 10^4\ N

Acceleration of the shark, a=1.25\ m/s^2

It is required to find the mass of the shark. Let m is the mass. Using second law of motion to find it as follows :

F = ma

Putting the value of F and a to find m

m=\dfrac{F}{a}\\\\m=\dfrac{2.5\times 10^4}{1.25}\\\\m=20,000\ kg

So, the shark's mass is 20,000 kg.

3 0
2 years ago
A particle of charge Q is fixed at the origin of an xy coordinate system. At t = 0 a particle (m = 0.727 g, q = 2.73 µC is locat
Montano1993 [528]

Answer:

Q = 12.466μC

Explanation:

For the particle to execute a circular motion, the electrostatic force must be equal to the centripetal force:

Fe = \frac{K*q*Q}{r^{2}} = \frac{m*V^{2}}{r}

Solving for Q:

Q = \frac{m*V^{2}*r}{K*q}

Taking special care of all units, we can calculate the value of the charge:

Q = 12.466μC

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2 years ago
If it takes a planet 2.8 × 108 s to orbit a star with a mass of 6.2 × 1030 kg, what is the average distance between the planet a
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Answer:

9.36*10^11 m

Explanation

Orbital velocity  v=√{(G*M)/R},

G = gravitational constant =6.67*10^-11 m³ kg⁻¹ s⁻²,

M = mass of the star

R =distance from the planet to the star.

v=ωR, with ω as the angular velocity and R the radius

ωR=√{(G*M)/R},

ω=2π/T,

T = orbital period of the planet

To get R we write the formula by making R the subject of the equation

(2π/T)*R=√{(G*M)/R}

{(2π/T)*R}²=[√{(G*M)/R}]²,

(4π²/T²)*R²=(G*M)/R,

(4π²/T²)*R³=G*M,

R³=(G*M*T²)/4π²,

R=∛{(G*M*T²)/4π²},

Substitute values

R=9.36*10^11 m

5 0
2 years ago
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