Questions:
1.Understand that objects are pulled downwards because of gravitational force.
2.Know that gravitational force is the attraction between things and the Earth.
3.Understand that gravitational force gives weight to an object.
4. Describe the effects of frictional force.
5. Recognize that an object that moves along a surface will eventually slow down and stop due to frictional force.
6. Compare how objects move on different surfaces.
7. Recognize that frictional force may prevent an object from starting to move.
8. Know that frictional force includes air and water resistances.
9. Explain frictional force in everyday life.
10. Suggest preventive measures against damages from frictional forces.
Answers:
1. When the ball's string is cut, it falls down.
2. The sun's gravity is strong, so it pulls Earth.
3. If you are 100lb on Earth, you weigh 117lb on Neptune.
4. Frictional force is like when a car starts to move.
5. Frictional force slows down objects.
6. A car goes fast on smooth surfaces but slow on hard surfaces.
7. Frictional force may stop for an object to move.
8. Some frictional force contain air and water resistance.
9. Frictional force is useful and harmful.
10. Use rollers and wheels and lubricants.
1.Understand that objects are pulled downwards because of gravitational force.
2.Know that gravitational force is the attraction between things and the Earth.
3.Understand that gravitational force gives weight to an object.
4. Describe the effects of frictional force.
5. Recognize that an object that moves along a surface will eventually slow down and stop due to frictional force.
6. Compare how objects move on different surfaces.
7. Recognize that frictional force may prevent an object from starting to move.
8. Know that frictional force includes air and water resistances.
9. Explain frictional force in everyday life.
10. Suggest preventive measures against damages from frictional forces.
Answers:
1. When the ball's string is cut, it falls down.
2. The sun's gravity is strong, so it pulls Earth.
3. If you are 100lb on Earth, you weigh 117lb on Neptune.
4. Frictional force is like when a car starts to move.
5. Frictional force slows down objects.
6. A car goes fast on smooth surfaces but slow on hard surfaces.
7. Frictional force may stop for an object to move.
8. Some frictional force contain air and water resistance.
9. Frictional force is useful and harmful.
10. Use rollers and wheels and lubricants.