Physics 2003 JAMB Past Questions - Question 9: The stylus of a phonograph record exerts a force of 7.7 x 10²N on a groove of radius 105m. Compute the pressure exerted by the stylus on the groove.

Correct Answer

A

Explanation

To compute the pressure exerted by the stylus on the groove of a phonograph record, you can use the formula for pressure:

Pressure (P) = Force (F) / Area (A)

In this case, you're given the force as 7.7 x 10^2 N and need to find the area over which this force is distributed. The area in this case is the contact area between the stylus and the groove.

The groove is given to have a radius of 105m. Assuming that the stylus exerts a force on the groove along a circular path, the contact area would be a circular area with a radius of 105m. The area of a circle is given by the formula:

A = π * r^2

Where:
A is the area
π (pi) is approximately 3.14159
r is the radius of the circle

Plugging in the values:

A = π * (105m)^2
A = 3.14159 * 11025 m^2
A ≈ 34637.38 m^2

Now that you have the contact area, you can calculate the pressure:

P = F / A
P = (7.7 x 10^2 N) / (34637.38 m^2)

Now, calculate the pressure:

P ≈ 0.0222 N/m^2

So, the pressure exerted by the stylus on the groove is approximately 0.0222 Newtons per square meter (N/m^2).