8. Which activity increases friction?
a. Increasing the mass of the object that is moving.
b. Use of lubricants in machines
c. Polishing the uneven surfaces
d. Use of ball bearings in rotating machines and shafts.
10. What should Lito do to avoid accident?
a. Walk carefully
b. Run fast c. Jump and slide on the floor d. Play with the scrub
11. Which does not affect friction?
a. Color of the involved objects
b. Mass of object
c. Area of contact
d. Texture of the surface of contact
12. There are 4 boxes on a slope. The mass of the red box is 10 kg., blue box is 5 kg and green box is 1
kg. It the wind blows the three boxes which one will move faster?
a. red box.
b. blue box
d. blue and green boxes
C. green box​