1. The kinds of Force Weight(w) w = m. g w = weight ( N ) m = mass ( kg )
g = gravitational acceleration ( m/s2 ) w

2. 2. Normal Force (N)
Normal force is the contact force which acts in perpendicular direction to the contact plane.
w = N w ≠ N
N = w cos α N N α w w

3. 3. String Tension Force ( T )
String tension Force is the force which is transmitted through a string or wire T F T T T

4. 4. Friction Force ( f )
Force which opposes the direction of objects motion is frictional force. v F f
Friction force

5. Free body diagram
N = w N w

6. T = w T w

7. N = w cosα N
W cos α
W sin α W

8. exercise
1. a cube at rest on smooth floor receives a horizontal force of 100 N and moves accelerated. If the cube has 5 kg in mass determine :
A. acceleration of cube
B. distance travelled by the cube after 10 second

9. 2. An object is rest on a smooth floor and it is applied force as in the following figure,if the object moves 10 m, determine : a. acceleration of the object b. mass of object c. Normal force.
80 N
120 N
45o

10. 3. Two object each 2 kg and 1 kg is connected with a string and pulled by a constant force of 24 N, as shown in the figure, then the magnitude of the string tension force is … kg 1 kg

11. 4. Look at the following figure, based on the figure determine the string tension force of T1 and T2 : T1
12 kg T2
8 kg

12. 5. look at following figure,based of figure determine : a
5. look at following figure,based of figure determine : a. Free body diagram b. the system acceleration c. force resultan on each cube d. contact force on each cube
F=400N
45 kg
20 kg
15kg

13. 6. Look at the values of the following figure
6. Look at the values of the following figure. If the mass of the object is 20 kg, the values of the tensile strength between T1 and T2 are …
60o
30o T1 T2 T

14. 7. A person with mass 60 kg is in lift which a moving downward with acceleration 3 m/s2. The presure of the person on the lift floor if the gravitational acceleration is 10 m/s2 is …

15. 8. Look at the pulley system in the following figure
8. Look at the pulley system in the following figure. The masses of the load A and B are 5 kg and 3 kg respectively. Calculate acceleration of the blocks system and tension of the string. B A