Physics Unit 2 - Section 2: Forces 0.0 / 5 ? PhysicsForces and MotionGCSEAQA Created by: CatherineCreated on: 21-05-13 11:42 What can forces do? Change the shape of an object, or its motion or its state of rest. 1 of 21 What is the unit of force? Newtons, N 2 of 21 When two forces interact what can we say about the forces acting? That they are exerting equal and opposite forces on each other. 3 of 21 What is resultant force? A single force that has the same effect as all forces acting on an object. 4 of 21 What happens if the resultant force is.... Zero? The object stays at rest or constant velocity 5 of 21 ....not zero? The velocity of an object will change. 6 of 21 How do we calculate the resultant force when an object is acted on by two forces acting along the same line? The resultant force is: 1. their sum if the forces are acting in the same direction. 2. their difference if the forces are in opposite directions. 7 of 21 How does the acceleration of an object depend on the size of the resultant force? The bigger the resultant force on an object, the greater the acceleration. 8 of 21 What effect does the mass of the object have on its accleration? The greater the mass of an object is, the smaller its acceleration is for a given force. 9 of 21 How do we calculate the resultant force on an object from its acceleration and its mass? Resultant force, N = mass, Kg x acceleration, m/s^2 10 of 21 What forces oppose the driving force of a car? Friction, and air resistance 11 of 21 What does the stopping distance of a vehicle depend on? The thinking and braking distance 12 of 21 What factors can increase the stopping distance of a car? Braking distance: High speed, poor weather conditions, poor maintenance. Thinking distance: Poor reactions and high speed. 13 of 21 What is the difference between mass and weight? Weight is the force of gravity on an object. Mass is the quantity of matter in an object. 14 of 21 What can we say about the motion of a falling object acted on only by gravity? An object acting on by gravity accelerates at about 10m/s^2 15 of 21 What is terminal velocity? The velocity of an object reaches when it is falling in a fluid. Weight = drag froce. 16 of 21 How do we measure the extension if an object when it is stretched? The extension is the difference between the length of the spring and the orginal length. 17 of 21 How does the extension of a spring vary with the force applied to it? It's directly proportional to the force applied. 18 of 21 What is the spring constant of a spring? The force per unit extension needed to stretch it. 19 of 21 How can the fuel economy of a vehicle be improved? By reducing the speed or fitting a wind delector. 20 of 21 What is an average speed camera? They're linked in pairs and measure the speed of a vehicle. 21 of 21
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