Answer:
a. 0.21 rad/s2
b. 2.205 N
Explanation:
We convert from rpm to rad/s knowing that each revolution has 2π radians and each minute is 60 seconds
200 rpm = 200 * 2π / 60 = 21 rad/s
180 rpm = 180 * 2π / 60 = 18.85 rad/s
r = d/2 = 30cm / 2 = 15 cm = 0.15 m
a)So if the angular speed decreases steadily (at a constant rate) from 21 rad/s to 18.85 rad/s within 10s then the angular acceleration is

b) Assume the grind stone is a solid disk, its moment of inertia is

Where m = 28 kg is the disk mass and R = 0.15 m is the radius of the disk.

So the friction torque is

The friction force is

Since the friction coefficient is 0.2, we can calculate the normal force that is used to press the knife against the stone

Answer:
1.5min
Explanation:
To solve the problem it is necessary to take into account the concepts related to Period and Centripetal Acceleration.
By definition centripetal acceleration is given by

Where,
V = Tangencial velocity
r = radius
With our values we know that


Therefore solving to find V, we have:



For definition we know that the Time to complete are revolution is given by




Answer:
58.8 N
Explanation:
The normal force is calculated as equal to the perpendicular component of the gravitational force.
Thus; N = mg
We are given m = 6 kg
Thus;
N = 6 × 9.8
N = 58.8 N
Thus, magnitude of normal force on the rock = 58.8 N

The correct choice is ~ A
Bikes don't require gasoline for their functioning, so it causes less air pollution.
Answer:
The time is
Explanation:
From the question we are told that
The period of the circuit is 
Generally voltage maximization of the capacitor occurs during the voltage minimization of the inductor and vise versa
So the time between the voltage maximization of the capacitor and that of the inductor is mathematically represented as

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