My question that I'm suppose the answer is: Two particles, A and B, are in uniform circular motion about a common center. The acceleration of particle A is 6.0 times that of particle B. Particle B takes 2.4 times as long for a rotation as particle A. What is the ratio of the radius of the motion of particle A to that of particle B?

The options are:

5:1

1:3

14:1

1:1

I'm very confused here because I don't understand how any of these choices can represent the answer. I know the acceleration of A is 6 times greater than B, and B takes 2.4 times longer to to complete a rotation compared to A. But how can I compare the motions, when it doesn't really give me anything to compare it to?

Respuesta :

Answer:

Explanation:

1:1 because the radius is common that means they are of the same radius just different acceleration

The ratio of the radius of the motion of particle A to that of particle B is 1:1

Solution:

Let v be the uniform circular motion, [tex]v=\frac{2 \times 3.14 \times R}{T} \rightarrow(1)[/tex]

centripetal acceleration be [tex]a=\frac{v^{2}}{R} \rightarrow(2)[/tex]

On substituting 1 in 2 we get,  [tex]a=\frac{\left[\frac{2 \times 3.14 \times R}{T}\right]^{2}}{R}=\frac{2 \times 3.14 \times R}{T^{2}} \rightarrow (3)[/tex]

Given, acceleration of A = 6x; B = x Time taken by A = t ; B = 2.4t For particle A, substituting the values,  

[tex]\begin{array}{l}{\Rightarrow 6 x=\frac{2 \times 3.14 \times R}{t^{2}}} \\\\ {\Rightarrow 6 x=\frac{6.28 R}{t^{2}}} \\\\ {\Rightarrow R=\frac{6}{6.28} \times x t^{2}} \\\\ {\Rightarrow R a=0.955 x t^{2}}\end{array}[/tex]

For particle B, substituting the values,

[tex]\begin{array}{l}{\Rightarrow x=2 \times 3.14 \times \frac{R}{(2.4 t)^{2}}} \\\\ {\Rightarrow x=\frac{6.28}{5.76} \times \frac{R}{t^{2}}} \\\\ {\Rightarrow R=\frac{5.76}{6.28} \times x t^{2}} \\\\ {R b=0.917 x t^{2}}\end{array}[/tex]

Therefore, the ratio of radii of A and B is Ra : Rb = 0.955 : 0:917 Approximately, it can be written as 1:1.