ID# 1990
| 1 | Contact forces are forces that act on objects through direct contact. True False |
| 2 | Friction【摩擦力】 is an example of non-contact force. True False Friction is an example of contact force. |
| 3 | Friction always opposes【抵抗】 the motion of an object. True False |
| 4 | The friction between the tyres of a moving car and the road surface is greater when the road surface is wet. True False The friction between the tyres of a moving car and the road surface is smaller when the road surface is wet. |
| 5 | Although friction can cause problems, it is useful in our daily life. True False |
| 6 | The faster an object moves in air, the greater the air resistance【空氣阻力】 acting on it. True False |
| 7 | Without friction, it would be easier to hold a pen. True False With friction, it would be easier to hold a pen. |
| 8 | Both magnetic force and the force of gravity are examples of non-contact force. True False |
| 9 | The force of gravity always pulls an object towards the centre of the Earth. True False |
| 10 | Mass and weight are the same concepts. True False In science, mass and weight are two different concepts. Mass is measured in kilograms(kgs) but weight is measured in newtons(N). |
| 11 | The mass of an object is the same on Earth and on different planets while its weight is different. True False |
| 12 | Mass and weight are both measured in kilograms(kgs). True False Mass is measured in kilograms(kgs) but weight is measured in newtons(N). |
| 13 | The weight of an object may vary from place to place in the universe but its mass remains unchanged. True False |
| 14 | The greater the mass of an object, the smaller the force of gravity acting on it by the Earth and the less it weights. True False The greater the mass of an object, the greater the force of gravity acting on it by the Earth and the more it weights. |
| 15 | The mass of an object on Earth becomes smaller when it is put into space. True False The mass of an object remains unchanged from place to place. |
| 16 | The force of gravity acting on each person bt the Earth is the same. True False |
| 17 | Forces always occur in pairs - action and reaction. True False |
| 18 | Action and reaction have the same size of force and they act on different bodies in same directions. True False Action and reaction have the same size of force and they act on different bodies in opposite directions. |
