Math  /  Algebra

Question40. (II) A 0.45kg0.45-\mathrm{kg} ball, attached to the end of a horizontal cord, is revolved in a circle of radius 1.3 m on a frictionless horizontal surface. If the cord will break when the tension in it exceeds 75 N , what is the maximum speed the ball can have?

Studdy Solution

STEP 1

1. The mass of the ball is 0.45kg 0.45 \, \text{kg} .
2. The radius of the circle is 1.3m 1.3 \, \text{m} .
3. The maximum tension the cord can withstand is 75N 75 \, \text{N} .
4. The surface is frictionless.
5. We are trying to find the maximum speed of the ball.

STEP 2

1. Understand the relationship between tension, mass, radius, and speed.
2. Write the formula for centripetal force.
3. Substitute known values into the formula.
4. Solve for the maximum speed.

STEP 3

Understand the relationship between tension, mass, radius, and speed.
The tension in the cord provides the centripetal force necessary to keep the ball moving in a circle. The formula for centripetal force Fc F_c is:
Fc=mv2r F_c = \frac{mv^2}{r}
where m m is the mass, v v is the speed, and r r is the radius.

STEP 4

Write the formula for centripetal force.
Since the tension in the cord is the centripetal force, we have:
T=mv2r T = \frac{mv^2}{r}
where T T is the tension.

STEP 5

Substitute known values into the formula.
Given T=75N T = 75 \, \text{N} , m=0.45kg m = 0.45 \, \text{kg} , and r=1.3m r = 1.3 \, \text{m} , substitute these into the equation:
75=0.45×v21.3 75 = \frac{0.45 \times v^2}{1.3}

STEP 6

Solve for the maximum speed.
First, isolate v2 v^2 by multiplying both sides by 1.3 1.3 :
75×1.3=0.45×v2 75 \times 1.3 = 0.45 \times v^2
97.5=0.45×v2 97.5 = 0.45 \times v^2
Next, divide both sides by 0.45 0.45 :
v2=97.50.45 v^2 = \frac{97.5}{0.45}
v2=216.67 v^2 = 216.67
Finally, take the square root of both sides to solve for v v :
v=216.67 v = \sqrt{216.67}
v14.72m/s v \approx 14.72 \, \text{m/s}
The maximum speed the ball can have is approximately:
14.72m/s \boxed{14.72 \, \text{m/s}}

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