a)
i) 120 s
ii) 1.57 m/s
b)
i) Refer to the attached diagram
ii) Up
c)
d) Greater than
Explanation:
The problem does not provide full details: consult the attachments for the complete text.
a)
The revolution period of the book equals the total duration needed for the book to make one full revolution.
By examining the graph, we can approximate the revolution period by calculating the time difference between two successive points of the book's motion that share the same shape.
We could use the time difference between two adjacent crests to estimate the period. The first crest is observed at t = 90 s, and the following crest appears at t = 210 s.
This results in the revolution period being
T = 210 - 90 = 120 s
ii)
The tangential speed of the book is computed as the ratio of the distance traveled over one revolution (i.e., the circumference of the wheel) to the revolution period.
Mathematically:
where
R represents the wheel radius
T = 120 s indicates the period
Based on the graph, the book reaches a maximum at x = +30 m and a minimum at x = -30 m, giving the diameter of the wheel as
d = +30 - (-30) = 60 m
This means the radius calculates to
R = d/2 = 30 m
So, the final speed is
b)
i) Please consult the attached free-body diagram for the book when at its lowest point.
Two forces act on the book at the lowest position:
- The weight of the book, represented as
where m denotes the book's mass and g stands for gravitational acceleration. This force functions downward.
- The normal force the bench exerts on the book is represented by N. This force acts upward.
ii)
While at its lowest position, the book maintains a horizontal motion at constant speed.
Nevertheless, the book is undergoing acceleration. Acceleration is defined as the rate of velocity change, which is vectorial, having both speed and direction. While the speed remains unchanged, the direction changes (upward), indicating the book has upward net acceleration.
According to Newton's second law, the net vertical force acting on the book corresponds with the vertical acceleration:
where F = net force, m = mass, a = acceleration. Thus, if a is non-zero, the upward net force must exist in line with the direction of the acceleration.
c)
As discussed in part b), there are two forces influencing the book at the lowest point:
- The weight, , directed downward
- The normal force from the bench, N, directed upward
Given that the book is in uniform circular motion, the net force must match the centripetal force , leading us to the equation:
where
represents the speed of the book
R stands for the radius of the circular path.
We derive an expression for the normal force:
d)
As per the discussions in parts c) and d):
- The normal force acting on the book at its lowest point becomes
- The weight (gravitational force) of the book is
Upon comparing these two equations, we conclude:
Thus, it is evident that the normal force exerted by the bench exceeds the weight of the book.
Answer:
The period of the pendulum measuring 16 m is double that of the 4 m pendulum.
Explanation:
Recall that the period (T) of a pendulum with length (L) is defined by:
where "g" denotes the local gravitational acceleration.
Since both pendulums are positioned at the same location, the value of "g" will be consistent for both, and when we compare the periods, we find:
Thus, the duration of the 16 m pendulum is two times that of the 4 m one.
Para calcular el peso utilizamos la fórmula:
Cuando tenemos dos cuerpos, empleamos la fórmula de la gravedad general:
Donde:
G = constante de gravedad =
Mp = masa de la persona = 882 / 9.81= 89.9kg
ME = masa de la Tierra =
r = distancia entre la Tierra y la persona
A partir de estas dos fórmulas, deducimos que los lados izquierdos son equivalentes, por lo tanto, los lados derechos también deben serlo.
Resolviendo esta ecuación para r:
r=6371116m = 6371.116km
Esta es la distancia desde el centro de la Tierra. El radio de la Tierra es 6370km y la altura sobre la superficie es 6371.116 - 6370 = 1.116km o 1116m.
Answer:
a. Angle= 28.82°
b. Approved. Although he might feel cold, he should be able to cross.
Explanation:
Velocity Vector
Velocity is a measure of how quickly something is moving in a specific direction. It is represented as a vector that has both magnitude and direction. If an object can only move in one direction, then speed can serve as the scalar equivalent of that velocity (only focusing on magnitude).
a.
The explorer aims to swim across a river to reach his campsite, as depicted in the image below. The river's velocity is vr and the explorer's swimming speed in still water is ve. If he were to swim straight towards the campsite, he would end up downstream due to the river's current. Therefore, he must swim at an angle that allows him to overcome the current while still moving towards his goal. This angle relative to the shore is what we need to determine. The explorer's speed can be broken down into its horizontal (vx) and vertical (vy) components. In order to counteract the river's flow:
We can calculate the vertical component of the explorer's swimming speed as
Thus
Finding the value of
Then the angle is given by
b.
The component of the explorer's velocity that goes horizontally is
This represents the actual velocity directed towards the campsite
Considering that
To find t
Calculating the duration for the explorer to cross the river
As this time is under the hypothermia threshold (300 seconds), the conclusion is
Approved. Although he will feel cold, he should manage to cross successfully.
