All Solved Examples of Chapter 4 Rotational & Circular Motion | Class 11 AQ Academy AQ Academy AQ Academy

 All Solved Examples of Chapter 4 Rotational & Circular Motion

Example 4.1

The platter of the hard drive of a computer rotates at 7300 rpm (a) What is the angular velocity of the platter’? (b) If the reading head of the drive is located 3.1 cm from the rotation axis , what is the linear speed of the point on the platter just below it? (c) If a single bit requires 0.55 pm of length along the direction of motion, how many bits per second can the writing head write when it is 3.1 cm from the axis?

 

 

Example 4.2

A motor cycle wheel turns 3620 times while being ridden for 6.50 minutes. What is the angular speed in rev/min (rpm)

 

Example 4.3

 

What is the magnitude of force and the centripetal acceleration of a car having mass of 300 kg following a curve of radius 500 m at a speed of 100 km/h? Also compare the acceleration with that due to gravity for this fairly gentle curve taken at highway speed.

 

 

Example 4.4

 

Curves on some test tracks and race courses, such as M-l Islamabad — Lahore Motorway, arc very steeply banked. This banking, with the support of tire friction and very stable car configurations. allows the curves to be taken at very high speed. To illustrate, calculate the speed at which a 100 m radius curve banked at 300 should be driven if the road were frictionless.

Approach

We first note that all terms in the expression for the ideal angle of a banked curve except for speed are known; thus, we need only rearrange it so that speed appears on the left-hand side and then substitute known quantities.

 

Example 4.5

 

The International Space Station orbits at an altitude of 400 km above the surface of the Earth, What is the space station’s orbital velocity?

 

 

 

 

Example 4.6

A basketball spinning on the finger of an athlete has angular velocity w = 120.0 rad/s. The moment of inertia of a sphere that is hollow, where M is the mass and R is the radius. If the basketball has a weight of 0.6000 kg and has a radius of 0.1200 m, what is the angular momentum of this basketball?

 

 

Worked Example 4.7

The biceps muscle exerts a vertical force on the lower arm, bent as shown in figure. For each case, calculate the torque about the axis of rotation through the elbow joint, assuming the muscle is attached 5 cm from the elbow as shown.