A ball is dropped from rest from a high window of a tall building and falls for 4 seconds. Neglecting air resistance, the final
1 answer:
Answer:
The final velocity of the ball is 39.2 m/s.
Explanation:
Given that,
A ball is dropped from rest from a high window of a tall building.
Time = 4 sec
We need to calculate the final velocity of the ball
Using equation if motion
Where, v = final velocity
u = initial velocity
g = acceleration due to gravity
t = time
Put the value into the formula
Hence, The final velocity of the ball is 39.2 m/s.
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Answer:
A) P.E = 138.44 J
B) The velocity of swing at bottom, v = 3.33 m/s
C) The work done, W = -138.44 J
Explanation:
Given,
The mass of the child, m = 25 Kg
The length of the swing rope, L = 2.2 m
The angle of the swing to the vertical position, ∅ = 42°
A) The potential energy at the initial position ∅ = 42° is given by the relation
P.E = mgh joule
Considering h = 0 for the vertical position
The h at ∅ = 42° is h = L (1 - cos∅)
P.E = mgL (1 - cos∅)
Substituting the given values in the above equation
P.E = 25 x 9.8 x 2.2 (1 - cos42°)
= 138.44 J
The potential energy for the child just as she is released, compared to the potential energy at the bottom of the swing is, P.E = 138.44 J
B) The velocity of the swing at the bottom.
At bottom of the swing the P.E is completely transformed into the K.E
∴ K.E = P.E
1/2 mv² = 138.44
1/2 x 25 x v² 138.44
v² = 11.0752
v = 3.33 m/s
The velocity of the swing at the bottom is, v = 3.33 m/s
C) The work done by the tension in the rope from initial position to the bottom
Tension on string, T = Force acting on the swing, F
=
= - 2.2 x 25 x 9.8 [cos0 - cos 42°]
= - 138.44 J
The negative sign in the in energy is that the work done is towards the gravitational force of attraction.
The work done by the tension in the ropes as the child swings from the initial position to the bottom of the swing, W = - 138.44 J
The Moment of Inertia of the Disc is represented by . (Correct answer: A)
Let suppose that the Disk is a Rigid Body whose mass is uniformly distributed. The Moment of Inertia of the element is equal to the Moment of Inertia of the entire Disk minus the Moment of Inertia of the Hole, that is to say:
(1)
Where:
- Moment of inertia of the Disk.
- Moment of inertia of the Hole.
Then, this formula is expanded as follows:
(1b)
Dimensionally speaking, Mass is directly proportional to the square of the Radius, then we derive the following expression for the Mass removed by the Hole ():
And the resulting equation is:
The moment of inertia of the Disc is represented by . (Correct answer: A)
Please see this question related to Moments of Inertia: brainly.com/question/15246709