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| Questão | Responda |
| What can forces do? | A force can change the shape of an object or change its motion or its state of rest. |
| What is the unit of force? | Newton (N) |
| What two objects interact, what can we say about the forces acting? | When two forces interact, they always exert(apply) equal and opposite forces on each other. |
| What is a resultant force? | It is a single force that has the same effect as all the forces acting on and object. |
| What happens if the resultant force on an object is zero? | The object stays at rest or at constant velocity. |
| What happens if the resultant force on an object is not zero? | The velocity of the object will change. |
| How do we calculate the resultant force when an object is acted on by two forces acting along the same line? | If two forces act on an object along the same line, the resultant force is: their sum if the force act in the same direction or if their difference if the forces act in opposite directions. |
| How does the acceleration of an object on the size of the resultant force? | The bigger the resultant force on an object is, the greater its acceleration is. |
| What effect does the mass of the object have on its acceleration? | The greater the mass of an object is, the smaller its acceleration is for a given force. |
| How do we calculate the resultant force on an object from its acceleration and its mass? | Resultant force (newtons,N)= Mass(kilograms) ___________________________ acceleration(metres per second squared) |
| What forces oppose the driving force of a car? | Friction and air resistance. |
| What does the stopping distance of a vehicle depend on? | Thinking distance and breaking distance. |
| What factors can increase the stopping distance of a vehicle? | High speed, poor weather conditions and poor maintenance all increase distance. Poor reaction time and high speed both increases thinking time. |
| What is the difference between mass and weight? | The weight of an object is the force of gravity on it. Its mass is the quantity of matter on it. |
| What is terminal velocity? | The velocity reached by an object when the drag force on it is equal and opposite to the force making it move. |
| How do we measure the extension of an object when it is stretched? | The difference is the difference between the length of the spring and its original length. |
| How does the extension of a spring vary with the force applied to it? | The extension of a spring is directly proportional to the force applied to it, provided the limit of proportionality is not exceeded. |
| What is the spring constant of a spring? | The spring constant of a spring is the force per unit extension needed to stretch it. |
| How can the fuel economy of road vehicles be improved? | By reducing the speed or fitting a wind deflector. |
| What is an average speed camera? | They measure speed of a vehicle. |
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