1774993
| Questão | Responda |
| Speed can be measure in..... [3] | #metres per second #kilometres per hour #miles per hour |
| The faster the speed of an object: [2] | the greater the distance it travels in a particular time the shorter the time it takes to travel a particular distance |
| How to calculate speed? | distance (m) speed = ____________________ (m/s) time (s) |
| Why is the average speed used? | The speed may change over a given distance, so an average distance over the whole journey is used |
| How to work out average distance? | Distance = (u + v) * t ----- 2 |
| Example question: Calculate the distance a car travels in 90 minutes if it's travelling at a constant speed of 80 km/h ? | distance = speed * time = 80 km/h * 1.5 hours = 120 km |
| How do speed cameras work? | They generally take 2 pictures of a vehicle a certain amount of time apart. the position of the vehicle in relation to the distance markings on the road in the 2 pictures can be used to calculate the vehicle's speed |
| What is the formula for measuring the speed of a vehicle on a speed camera? | speed of car = distance travelled between pictures / time taken between 1st and 2nd picture |
| (Distance-time graphs) The steeper the gradient.... | the greater the speed |
| distance - time graphs) a straight diagonal line shows... | a constant speed |
| (distance-time graphs) a straight horizontal line shows..... | No movement (stationary) |
| (distance-time graphs) a steeper diagonal line means.... | an increase in speed (object is going faster than it was before) |
| (distance-time graphs) a diagonal line going downwards means.... | object is going backwards |
| How do you work out the speed of an object on a distance-time graph? | take any 2 points on the graph and read off the distance travelled for that part of the journey and the time taken to get there |
| The acceleration / deceleration of an object is..... ? | the change in speed per second |
| How do you measure acceleration and deceleration? | acceleration = metres / second squared deceleration = -metres / second squared |
| How do you work out the acceleration of a moving object? | acceleration = (final velocity - initial velocity) / time |
| Example question: A car accelerates at 1.5 m/s2 for 12 seconds. Calculate the change in speed of the car | change in speed = acceleration * time taken =1.5 m/s2 * 12 = 18 m/s |
| (speed-time graphs) a horizontal line means... | No acceleration (0 m/s2) |
| (speed-time graphs) a positive diagonal line shows.... | acceleration |
| (speed-time graphs) a negative diagonal line shows.. | deceleration |
| (speed-time graphs) the area underneath the speed-time can be used to measure.... | distance travelled |
| How would you calculate the total distance travelled on a speed-time graph? | Cut the graph into triangles and rectangles, then find the area for each shape and add them all up. REMEMBER! area of rectangle = width * height area of a triangle = 1/2 * base * height |
| What is Force measured in? | Newtons |
| Forces can cause objects to....? | accelerate |
| Weight causes an object to have.... ? | gravity (weight can also be called gravity) |
| How does friction affect a car? | it slows it down |
| What happens when a sky diver opens up a parachute mid-jump? | Air resistance - Air resistance causes the skydiver to slow down A LOT when the parachute opens. |
| What happens to a sky-diver mid-jump when air resistance and weight are balanced? | they stay at a constant speed |
| if an unbalanced force acts, the acceleration of an object will depend on: ? [2] | #the force applied to the object #the mass of the object |
| more force = ... ? | = more acceleration |
| more mass = ... ? | = less acceleration |
| What is the formula for the relationship between force, mass and acceleration force (N) = .... ? | = mass (kg) * acceleration (m/s2) |
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