An athlete prepares to throw a 2.0-kilogram discus. His arm is 0.75 meters long. He spins around several times with the discus at the end of his outstretched arm so that the discus reaches a velocity of 5.0 m/s.

What is the centripetal force acting on the discus?

A. 27 N
B. 9.4 N
C. 66 N
D. 14 N



Answer :

To find the centripetal force acting on the discus, we can use the following formula for centripetal force (F):

[tex]\[ F = \frac{m v^2}{r} \][/tex]

where:
- [tex]\( m \)[/tex] is the mass of the object,
- [tex]\( v \)[/tex] is the velocity,
- [tex]\( r \)[/tex] is the radius.

Let's apply the values provided in the problem:
- Mass ([tex]\( m \)[/tex]) = 2.0 kilograms,
- Velocity ([tex]\( v \)[/tex]) = 5.0 meters per second,
- Radius ([tex]\( r \)[/tex]) = 0.75 meters.

Now, we substitute these values into the formula:

[tex]\[ F = \frac{2.0 \, \text{kg} \times (5.0 \, \text{m/s})^2}{0.75 \, \text{m}} \][/tex]

First, calculate the velocity squared:

[tex]\[ (5.0 \, \text{m/s})^2 = 25 \, \text{m}^2/\text{s}^2 \][/tex]

Next, compute the mass times the velocity squared:

[tex]\[ 2.0 \, \text{kg} \times 25 \, \text{m}^2/\text{s}^2 = 50 \, \text{kg} \cdot \text{m}^2/\text{s}^2 \][/tex]

Finally, divide by the radius:

[tex]\[ F = \frac{50 \, \text{kg} \cdot \text{m}^2/\text{s}^2}{0.75 \, \text{m}} \][/tex]

[tex]\[ F = 66.66666666666667 \, \text{N} \][/tex]

The numerical result rounded to the nearest whole number is 67 N, which is closest to the option 66 N given in the problem.

Therefore, the centripetal force acting on the discus is:

[tex]\[ \boxed{66 \, \text{N}} \][/tex]