Magnets facing the same way <span />
Answer:
Final Speed of Dwayne 'The Rock' Johnson = 15.812 m/s
Explanation:
Let's start out with finding the force acting downwards because of the mass of 'The Rock':
Dwayne 'The Rock' Johnson: 118kg x 9.81m/s = 1157.58 N
Now the problem also states that the kinetic friction of the desk in this problem is 370 N
Since the pulley is smooth, the weight of Dwayne Johnson being transferred fully, and pulls the desk with a force of 1157.58 N. The frictional force of the desk is resisting this motion by a force of 370 N. Subtracting both forces we get the resultant force on the desk to be: 1157.58 - 370 = 787.58 N
Now lets use F = ma to calculate for the acceleration of the desk:
787.58 = 63 x acceleration
acceleration = 12.501 m/s
Finally, we can use the motion equation:

here u = 0 m/s (since initial speed of the desk is 0)
a = 12.501 m/s
and s = 10 m
Solving this we get:


Since the desk and Mr. Dwayne Johnson are connected by a taught rope, they are travelling at the same speed. Thus, Dwayne also travels at 15.812 m/s when the desk reaches the window.
The best answer to go with is b
The time spent in the air by the ball at the given momentum is 6.43 s.
The given parameters;
- <em>momentum of the ball, P = 0.9 kgm/s</em>
- <em>weight of the ball, W = 0.14 N</em>
The impulse experienced by the ball is calculated as follows;

where;
is impulse
is change in momentum
The time of motion of the ball is calculated as follows;

Thus, the time spent in the air by the ball at the given momentum is 6.43 s.
Learn more here:brainly.com/question/13468390
Answer:
changing the polarity or direction of the battery changes the sign of the voltage and the current
Explanation:
The sign of current and voltage are due to established conventions.
The way that a DC circuit with negative current values is by changing the polarity of the power source or by inverting the battery, this creates that the electrons move in the opposite direction
Changing the battery also changes the direction of the power difference, since the potential from positive to negative, in most cases negative is assigned a potential of zero volts
In summary, changing the polarity or direction of the battery changes the sign of the voltage and the current