F2 Forces – Multiple Choices

The unit of force is

A force can change the __________ of an object.

1. speed
2. weight
3. direction of motion
4. shape

Forces can be measured by

1. ammeter
2. newton balance
3. voltmeter
4. spring balance

Catching a football will change its

1. speed
2. direction of motion
3. shape

Striking a volleyball changes its

1. speed
2. direction of motion
3. shape

Pressing on an inflated balloon【充氣氣球】 changes its

1. speed
2. direction of motion
3. shape

For an  object sliding on a surface, the friction can be reduced【降低】 by

1. using rolling beads
2. adding lubricant between the object and the surface
3. supporting the object on an air cushion

Which of the following things/objects have streamlined【流線型】 shape to reduce resistance?

1. luggage
2. fish
3. racing cars
4. rollers on the conveyor belt

Which of the following things/objects using rolling beads to reduce resistance?

1. window hinges
2. luggage
3. hovercraft
4. rollers on the conveyor belt

Which of the following things/objects using air cushion to reduce resistance?

1. racing cars
2. luggage
3. hovercraft
4. air hockey

Which of the following things/objects using lubricant to reduce resistance?

1. window hinges
2. take a ring off a finger
3. hovercraft
4. air hockey

Which of the following are an example of using friction positively?

1. bath mats
2. parachutes
3. window hinges
4. bicycle brakes【自行車剎車】