? A wheel initially at rest ,is rotated with uniform angular accelerat...
Here,
initial angular velocity = 0m/s.
angular acceleration = A rad/s^2
angular disp. = wt + 1/2At^2
a1 = 0 + 1/2*A(1)^2. (as t = 1s)
a1 = 1/2*A
now, when t=2s
a' = 0 + 1/2*A(2)^2
a' = 1/2*4A
a' = 2A
therefore,
a2 = a' - a1
a2 = 2A - A/2
a2 = 3A/2
so now,
a2/a1 = 3/2A ÷ A/2
therefore,
a2/a1 = 3
Hope it helps.
? A wheel initially at rest ,is rotated with uniform angular accelerat...
Problem:
A wheel initially at rest is rotated with uniform angular acceleration. The wheel rotates through an angle a1 in the first one second and through an additional angle a2 in the next one second. Find the ratio a2/a1.
Solution:
Let's assume the initial angular velocity of the wheel is ω0 and the angular acceleration is α.
Step 1: Finding the angular velocity after 1 second
Using the equation of motion for rotational motion:
ω = ω0 + αt
After 1 second, ω1 = ω0 + α(1) = ω0 + α
Step 2: Finding the angle rotated in the first second (a1)
Using the equation for angular displacement:
θ = ω0t + (1/2)αt^2
Substituting the values, we get:
a1 = ω0(1) + (1/2)α(1)^2
= ω0 + (1/2)α
Step 3: Finding the angular velocity after 2 seconds
Using the equation of motion for rotational motion:
ω = ω0 + αt
After 2 seconds, ω2 = ω0 + α(2) = ω0 + 2α
Step 4: Finding the angle rotated in the second second (a2)
Using the equation for angular displacement:
θ = ω0t + (1/2)αt^2
Substituting the values, we get:
a2 = ω0(1) + (1/2)α(2)^2
= ω0 + 2α
Step 5: Finding the ratio a2/a1
Dividing a2 by a1:
a2/a1 = (ω0 + 2α)/(ω0 + (1/2)α)
Simplifying the expression:
a2/a1 = (2(ω0 + α))/(ω0 + (1/2)α)
= 2(1 + α/ω0)/(1 + (1/2)(α/ω0))
Since the wheel is initially at rest, ω0 = 0. Therefore, α/ω0 is undefined. Hence, we cannot determine the exact value of a2/a1.
Therefore, the given answer (c) is incorrect. The correct answer should be undefined.
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