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
Their skin is thin and moist so they can breath underwater
Answer:
<h2>300 J</h2>
Explanation:
The potential energy of a body can be found by using the formula
PE = mgh
where
m is the mass
h is the height
g is the acceleration due to gravity which is 10 m/s²
From the question we have
PE = 2 × 10 × 15
We have the final answer as
<h3>300 J</h3>
Hope this helps you
Answer:
0.248 m
Explanation:
The period of a simple pendulum is given by
where
L is the length of the pendulum
g is the acceleration of gravity
The pendulum in the problem passes its lowest point twice every second: this means: this means that it makes one complete oscillation in one second, so its period is 1 second:
T = 1 s
And using
We can rearrange the equation above to find L, the length of the pendulum: