Rotational rigid body 5

Rotational rigid body 4

Example:

A 5.00 kg object placed on a frictionless horizontal table is connected to a string that passes over a pulley and then is fastened to a hanging 9.00 kg object. The pulley has a radius of 0.250 m and moment of inertia I. The block on the table is moving with a constant acceleration of 2.00 m s^-2.

(a)    Sketch free body diagrams of both objects and pulley.

(b)   Calculate T₁ and T₂ the tensions in the string.

(c)    Determine I.

Rotational of rigid body 3

A see-saw consists of a uniform board of mass 10 kg and length 3.50 m supports a father and daughter with masses 60 kg and 45 kg, respectively as shown in Figure 8.9. The fulcrum is under the centre of gravity of the board.

Suggested solution

Rotational of rigid body 2

Taken from sdsu-physics.org

Jom Mudah Belajar Tork!

Mencari nilai tork lebih mudah dengan

Kaedah LPT merupakan satu kaedah pengajaran untuk menentukan jarak serenjang antara daya dengan paksi putaran. Kaedah ini boleh dilaksanakan dalam 3 langkah mudah seperti berikut :

1. Lengthen the Force, F: Panjangkan daya, F
2. Draw a parallel line that passes through the axis of  rotation: Lukiskan garisan selari melalui paksi putaran
3. Draw a perpendicular line between the two parallel lines. That is the perpendicular distance, r: Lukiskan garisan serenjang di antara kedua-dua garisan selari. Itulah jarak serenjang, r yang diperlukan.

http://lptkms.blogspot.com/

Rotation of rigid body 1

Gravitation 3

Gravitation 2

What is escape velocity?

• If you throw an object straight up, it will rise until the the negative acceleration of gravity stops it, then returns it to Earth. Gravity's force diminishes as distance from the center of the Earth increases, however. So if you can throw the object with enough initial upward velocity, so that gravity's decreasing force can never quite slow it to a complete stop, it's decreasing velocity can always be just high enough to overcome gravity's pull. The initial velocity needed to achieve that condition is called escape velocity. Answered by: Paul Walorski, B.A. Physics, Part-time Physics Instructor 

• Escape velocity is defined to be the minimum velocity an object must have in order to escape gravitational field of the Earth, that is, escape the Earth without ever falling back. The object must have greater energy than its gravitational binding energy to escape the Earth's gravitational field. So,

Kinetic energy (object) = Gravitational potential energy (Earth)

m = mass of the object

M = mass of the Earth

G = gravitational conctant

R = radius of the Earth

v = escape velocity

• The value evaluates to be approximately 11 000 m/ s. So, the object which has this velocity at the surface of the Earth, will totally escape the Earth's gravitational field. Answered by: Yasar Safkan, B.S. Phsyics Ph.D. Candidate, M.I.T.

Credit to: 

Gravitation 1

Circular motion 4

Vertical circular motion

Circular motion 3

Horizontal circular motion

Circular motion 2

Circular motion 1

Work 3

Example

Work 2

Work 1