Answer:
Average speed=1.5 m/s
Frequency of pendulum=93.75Hz
Explanation:
We are given
Frequency,
Average wavelength =
Speed of pendulum,
Wavelength,
We have to find the average speed and frequency of pendulum.
We know that
Speed,
Using the formula
Average speed,
Hence, the average speed =1.5m/s
Frequency,
Using the formula
Hence, the frequency of a pendulum=93.75Hz
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