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1.2 m

B
PROBLEM 15.40
Collar B moves upward with a constant velocity of 1.5 m/s. At the instant
when = 50°, determine (a) the angular velocity of rod AB, (b) the velocity
of end A of the rod.

1 Answer

2 votes

Answer: To solve this problem, we can use the principles of kinematics and geometry. We'll need to find the angular velocity of rod AB (ω_AB) and the velocity of end A of the rod (v_A).

Given information:

Velocity of collar B (v_B) = 1.5 m/s

Angle (θ) = 50 degrees

Let's break down the problem into two parts:

(a) Finding the angular velocity of rod AB (ω_AB):

We can use the relationship between linear velocity and angular velocity for a rotating object:

v = r * ω

Where:

v is the linear velocity,

r is the distance from the axis of rotation to the point of interest, and

ω is the angular velocity.

In this case, we are interested in point A on the rod. So, we need to find the distance from the axis of rotation (which is at point B) to point A. This distance is equal to the length of the rod, which is 1.2 meters.

v_A = r * ω_AB

Given:

v_B = 1.5 m/s (velocity of collar B)

r_AB = 1.2 m (length of the rod)

We can rearrange the equation to solve for ω_AB:

ω_AB = v_A / r_AB

Now, we need to find v_A.

(b) Finding the velocity of end A of the rod (v_A):

Since collar B is moving vertically with a constant velocity, the horizontal component of its velocity is zero. The velocity of A can be found using vector addition:

v_A = v_B_horizontal

To find the horizontal component of v_B, we can use trigonometry. The vertical component of v_B is v_B, and we can find the horizontal component as follows:

v_B_horizontal = v_B * cos(θ)

Given:

θ = 50 degrees

v_B = 1.5 m/s

Now, let's calculate v_B_horizontal:

v_B_horizontal = 1.5 m/s * cos(50 degrees)

Calculate this value.

Now that we have v_B_horizontal, we can use it to find v_A:

v_A = v_B_horizontal

Now, we have v_A, and we can use it to calculate ω_AB:

ω_AB = v_A / r_AB

Calculate this value.

So, you should have calculated the values for both (a) the angular velocity of rod AB (ω_AB) and (b) the velocity of end A of the rod (v_A).

answered
User Plaetzchen
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