An initially stationary 4.3 kg object accelerates horizontally and uniformly to a speed of 11 m/s in 3.4 s. (a) In that 3.4 s in
2 answers:
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The work done is 375 J
Explanation:
The work done by a force in moving an object is given by
where
F is the magnitude of the force
d is the displacement
is the angle between the direction of the force and the displacement
In this problem,
F = 75 N is the force applied to the couch
d = 5 m is the displacement
Assuming the force applied to the couch is parallel to the motion,
And so, the work done is
Learn more about work:
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Answer:
a) -1.325 μC
b) 4.17μC
Explanation:
First, you need to know that charge is conserved. So, the adition of the charges, as there is no lost in charge, should always be the same. Also, after the wire is removed, both spheres will have the same charge, trying to find equilibrium. In summary:
We know both q1f and q2f must be positive, because the negative charge at the beginning was the the smaller.
The electrostatic force is equal to:
K is the Coulomb constant, equal to 9*10^9 Nm^2/C^2
Now, we are told that the electrostatic force after the wire is equal to 0.0443 N:
Originally, the force is negative because it was an attraction force, therefore, its direction was opposite to the direction of the repulsive force after the wire:
Solving the quadratic equation:
for this values q_1 wil be:
So as you can see, the negative charge will always be -1.325 μC and the positive 4.17μC
(a) The angular acceleration of the wheel is given by
where
and 
are the initial and final angular speed of the wheel, and t the time.
In our problem, the initial angular speed is zero (the wheel starts from rest), so the angular acceleration is
(b) The wheel is moving by uniformly rotational accelerated motion, so the angle it covered after a time t is given by
where
is the initial angular speed. So, the angle covered after a time t=3.07 s is
where
In our problem, the initial angular speed is zero (the wheel starts from rest), so the angular acceleration is
(b) The wheel is moving by uniformly rotational accelerated motion, so the angle it covered after a time t is given by
where