A student on an amusement park ride moves in a circular path with a radius of 3.5 meters once every 8.9 seconds. What is the ave
1 answer:
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1) Initial upward acceleration:
2) Mass of burned fuel:
Explanation:
1)
There are two forces acting on the rocket at the beginning:
- The force of gravity, of magnitude , in the downward direction, where
is the rocket's mass
is the acceleration of gravity
- The thrust of the motor, T, in the upward direction, of magnitude
According to Newton's second law of motion, the net force on the rocket must be equal to the product between its mass and its acceleration, so we can write:
(1)
where a is the acceleration of the rocket.
Solving for a, we find the initial acceleration:
2)
When the rocket reaches an altitude of 5000 m, its acceleration has increased to
The reason for this increase is that the mass of the rocket has decreased, because the rocket has burned some fuel.
We can therefore rewrite eq.(1) as
where
is the new mass of the rocket
Re-arranging the equation and solving for m', we find
And since the initial mass of the rocket was
This means that the mass of fuel burned is
The speed of the elevator at the beginning of the 8 m descent is nearly 4 m/s. Hence, option A is the correct answer.
We are given that-
the mass of the elevator (m) = 1000 kg ;
the distance the elevator decelerated to be y = 8m ;
the tension is T = 11000 N;
let us determine the acceleration 'a' by using Newton's second law of motion.
∑Fy = ma
W - T = ma
(1000kg x 9.8 m/s² ) - 11000N = 1000 kg x a
9800 - 11000 = 1000
a = - 1.2 m/s²
Using the equation of kinematics to determine the initial velocity.
² =
² + 2ay
= √ ( 2 x 1.2m/s² x 8 m )
= √19.2 m²/s²
= 4.38 m/s ≈ 4 m/s
Hence, the initial velocity of the elevator is 4m/s.
Read more about the Equation of kinematics:
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Answer:
The magnitude of electrostatic force on each charge is quarter of the magnitude of initial electrostatic force. ( ¹/₄ F)
Explanation:
The electrostatic force between two charges is given by Coulomb's law;
where;
Q₁ and Q₂ are the magnitude of the charges
r is the distance between the charges
k is Coulomb's constant
Since the charges are identical;
Q₁ = Q
Q₂ = Q
the electrostatic force experienced by each charge is given by;
When each of the spheres has lost half of its initial charge;
Q₁ = Q/2
Q₂ = Q/2
Therefore, the magnitude of electrostatic force on each charge is quarter of the magnitude of initial electrostatic force.