P5

Question 1

explain the difference between scalar and vector quantities

Answer 1

Vector quantities have two characteristics, a magnitude and a direction. Scalar quantities have only a magnitude.

Question 2

true or false time is a vector quantity

Answer 2

False

Question 3

what is the difference between contact and non-contact forces

Answer 3

A non-contact force is a force which acts on an object without coming physically in contact with it.

Question 4

explain the difference between mass and weight

Answer 4

Mass is a measure of how much matter there is in an object, while weight is a measure of the size of the pull of gravity on the object

Question 5

what is the formula for calculating the weight of an object

Answer 5

weight (N) = mass (Kg) x gravitational field strength (N/kg)

Question 6

what is a free body diagram

Answer 6

a diagram that describes the forces acting on an isolated object or a system

Question 7

what is a resultant force

Answer 7

When a system of forces is acting on an object, the difference between the forces is called the Resultant force.

Question 8

give the formula for calculating the work done by a force, and explain what each symbol means.

Answer 8

W = F x s
work force distance
done (N) (M)
(J)

Question 9

how many joules of work does 1 Nm equal

Answer 9

1 joule

Question 10

describe the forces acting on an object in equilibrium

Answer 10

If the size and direction of the forces acting on an object are exactly balanced, then there is no net force acting on the object and the object is said to be in equilibrium.

Question 11

what is the difference between elastic an inelastic deformation

Answer 11

elastic deformation is reversed when the force is removed. inelastic deformation is not fully reversed when the force is removed

Question 12

give the equation that relates force, extension and the spring constant of an object

Answer 12

F (force) = K (spring constant) X E (extension)

Question 13

what is the limit of proportionality

Answer 13

the point beyond which Hooke’s law is no longer true when stretching a material

Question 13

give the equation used to find the energy in an elastic object’s elastic potential energy store.

Answer 13

Ee = ½ × k × e2
Where: Ee = elastic potential energy in Joules (J) k = spring constant in Newtons per metre (N/m) e = extension in metres (m)

Question 14

what is the difference between displacement and distance

Answer 14

The complete length of the path between any two points is called distance. Displacement is the direct length between any two points when measured along the minimum path between them.

Question 15

define acceleration in terms of velocity and time

Answer 15

Acceleration is the change in speed or velocity of an object over a certain time

Question 16

what does the term uniform acceleration mean

Answer 16

If an object’s speed (velocity) is increasing at a constant rate then we say it has uniform acceleration

Question 17

what does the gradient represent for a
1) distance time graph
2) velocity time graph

Answer 17

1) In a distance-time graph, the gradient of the line is equal to the speed of the object
2) the acceleration of the object.

Question 18

what is terminal velocity

Answer 18

the highest velocity attained by an object falling through a fluid

Question 19

what causes terminal velocity

Answer 19

when the sum of the drag force and the buoyancy is equal to the downward force of gravity acting on the object.

Question 20

state newtons three laws of motion

Answer 20

In the first law, an object will not change its motion unless a force acts on it. In the second law, the force on an object is equal to its mass times its acceleration. In the third law, when two objects interact, they apply forces to each other of equal magnitude and opposite direction.

Question 21

what is inertia

Answer 21

a property of matter that causes it to resist changes in velocity

Question 22

what is the stopping distance of a vehicle

Answer 22

the total distance you travel before you apply the brakes, plus the distance you travel while the brakes slow you down

Question 23

how can the stopping distance of a vehicle be calculated

Answer 23

stopping distance = thinking distance + braking distance

Question 24

sate 4 things that can affect the breaking distance of a vehicle

Answer 24

speed, breaks, tyre pressure and road conditions

Question 25

give 2 things that affect a persons reaction times

Answer 25

any 2 of: age, gender, physical fitness, fatigue, distraction, alcohol, personality type,

Question 26

what is the average reaction time

Answer 26

between 150 and 300 milliseconds

Question 27

briefly describe an experiment to compare peoples reaction times

Answer 27

Ask a friend to put their thumb and index finger slightly open at the bottom of the ruler, with the ruler between their fingers. Drop the ruler and record the measurement on the ruler where the other persons fingers are

Question 27

state the formula used to calculate an objects momentum

Answer 27

p=mv: momentum (p) is equal to mass (m) times velocity (v).