Answer:
Explanation:
Given that,
A point charge is placed between two charges
Q1 = 4 μC
Q2 = -1 μC
Distance between the two charges is 1m
We want to find the point when the electric field will be zero.
Electric field can be calculated using
E = kQ/r²
Let the point charge be at a distance x from the first charge Q1, then, it will be at 1 -x from the second charge.
Then, the magnitude of the electric at point x is zero.
E = kQ1 / r² + kQ2 / r²
0 = kQ1 / x² - kQ2 / (1-x)²
kQ1 / x² = kQ2 / (1-x)²
Divide through by k
Q1 / x² = Q2 / (1-x)²
4μ / x² = 1μ / (1 - x)²
Divide through by μ
4 / x² = 1 / (1-x)²
Cross multiply
4(1-x)² = x²
4(1-2x+x²) = x²
4 - 8x + 4x² = x²
4x² - 8x + 4 - x² = 0
3x² - 8x + 4 = 0
Check attachment for solution of quadratic equation
We found that,
x = 2m or x = ⅔m
So, the electric field will be zero if placed ⅔m from point charge A, OR ⅓m from point charge B.
Answer: Third option
F = 250w
Explanation:
The impulse can be written as the product of force for the time interval in which it is applied.
You can also write impulse I as the change of the linear momentum of the ball
So:
We want to find the force applied to the ball. We know that
milliseconds = 0.03 seconds
The initial velocity 
is zero.
The final speed 
So
We must express the result of the force in terms of the weight of the ball.
We divide the expression between the acceleration of gravity
The answer is the third option
Answer:
an electromagnet is a metal which has the ability to turn into a magnet on passing electricity through it .
But once the electric flow is withdrawn the circuit breaks and it no more behaves like a magnet.
but this is not so in permanent magnets
Explanation:
thus electromagnet is used in magnetic cranes bcoz their magnetism can be controlled conveniently.
Answer:
- <u>First choice:</u><u><em> Because the mass of the cannon ball is much less than the cannon</em></u>
Explanation:
Indeed, <em>Newton's Third Law</em>, i.e. the action-reaction law, states that any action (force) will have a reaction (force) of same magnitude but opposite direction.
That means that when a cannon goes off the cannon ball exerts a force on the cannon and the cannon exerts the same force back on the cannon ball.
To find out how much the cannon ball and the cannon itsel move, you must consider Newton's second law.
- F = m×a (force equal mass times acceleration).
Clearing the acceleration you get:
Then, since the mass is in the denominator and both the force that the cannon ball exerts on the cannon and the cannon exerts on the cannon ball are equal in magnitude, then the body that has the smaller mass (the cannon ball) will experience a greater acceleration, which is stated by the first choice: because the mass of the cannon ball is much less than the cannon.
