Exercise of Energy

1. If the acceleration due to gravity in a certain place is 10 m/s2, then calculate the potential energy of a body, which mass is :
a. 4 kg at the height of 25 m above the ground
b. 1.5 x 10-5 gram at the height of 6 x 106 cm
2. Calculate the kinetic energy owned by :
a. car of 2500 kg which moves velocity of 72 km/hour
b. a ball 80 gram which moves with velocity of 15 m/s
3. A stalled car is pushed by 3 people. They are Iman with pulling force of 300 N, Ferry of 500 N, and Dias with pulling force of 600 N. The car moves as far as 200 m from the initial place.
a. What is work of each people ?
b. What is total force that moves the car ?
c. What is total work of the three people ?

Growth and Development

For students class 8I, answer question below in your task books, for next meeting.
1. write down the difference between growth and development!
2. What is the definition of plant growth?
3. write down the difference between primary growth and secondary growth in plant!
4. write down the various kinds of growth region based on their activity!
5. Write down and explain the theory about growth point in plant!

MOTION

Answer the question below in your tasks book for next meeting.
1. A boy walks 40m due east from a point P and then another 30m due north and finally 40m due west.
(a). What is the total distance travelled?
(b). What is the boy's displacement from P?