Mechanics

Question 1

Scalars

Answer 1

Describe only a magnitude.

Question 2

Vectors

Answer 2

Describe magnitude and direction.

Question 3

Example of scalars

Answer 3

Distance, speed, mass, temperature

Question 4

Example of vectors

Answer 4

Displacement, velocity, force/weight, acceleration

Question 5

When should scale drawings be used?

Answer 5

When vectors are at angles other than 90 degrees.

Question 6

What must be happening for an object to be in equilibrium?

Answer 6

The sum of all forces acting on it must be zero.

Question 7

Moment

Answer 7

Moment = Force X Perpendicular distance to line of action of force from the point

Question 8

Couple

Answer 8

A couple is a pair of force within the same plane where the two forces are equal in magnitude but act in opposite directions.

Question 9

Moment of a couple

Answer 9

Force X Perpendicular distance between the lines of action of forces.

Question 10

Principle of moments

Answer 10

For an object in equilibrium, the sum of anticlockwise moments about a pivot is equal to the sum of clockwise moments.

Question 11

Center of mass

Answer 11

The point at which an object’s mass acts.

Question 12

Uniform

Answer 12

its centre of mass will be exactly at its center.

Question 13

Speed

Answer 13

Scalar quantity which describes how quickly an object is travelling

Question 14

Displacement

Answer 14

The overall distance travelled from the starting position.

Question 15

Velocity

Answer 15

The rate of change of displacement.

Question 16

Acceleration

Answer 16

The rate of change of velocity.

Question 17

Instantaneous velocity

Answer 17

The velocity of an object at a specific point in time.

Question 18

Average velocity.

Answer 18

The velocity of an object over a specified time frame.

Question 19

Uniform acceleration

Answer 19

Where the acceleration of an object is constant.

Question 20

Acceleration time graphs

Answer 20

Represent the change in velocity over time. The area under the graph is change in velocity.

Question 21

Velocity time graphs

Answer 21

Represent the change in velocity over time. Therefore the gradient of a VT graph is acceleration. Area is displacement.

Question 22

Displacement time graphs

Answer 22

Change in displacement over time, their gradient represents velocity.

Question 23

Free fall

Answer 23

Where an object experiences an acceleration of g.

Question 24

Friction

Answer 24

The force which opposes the motion of an object. They convert kinetic energy into other forms.

Question 25

Magnitude of air resistance

Answer 25

Increases as the speed of the object increases.

Question 26

Lift

Answer 26

An upwards force which acts on objects travelling in a fluid. Acts perpendicular to the direction of fluid flow.

Question 27

Terminal speed

Answer 27

Occurs where the frictional forces acting on an object and driving forces are equal. No resultant force no acceleration. Object travels at a constant speed.

Question 28

Skydiver terminal speed example

Answer 28

- As they leave the plane, they accelerate as their weight is greater than the air resistance. - As the skydiver's speed increases, the magnitude of air resistance also increases. This continues until the force of weight and air resistance become equal = terminal velocity is reached.

Question 29

Air resistance

Answer 29

Affects both the vertical and horizontal components of a projectile's motion.

Question 30

Newton's first law

Answer 30

An object will remain at rest or travelling at a constant velocity, until it experiences a resultant force.

Question 31

Newton's second law

Answer 31

The acceleration of an object is proportional to the resultant force experienced by an object. F=ma

Question 32

Newton's third law

Answer 32

For each force experienced by an object, the object exerts an equal and opposite force.

Question 33

Free body diagram

Answer 33

A diagram which shows all the forces that act upon an object.

Question 34

Momentum

Answer 34

The product of mass and velocity of an object.

Question 35

What happens to momentum in any interaction?

Answer 35

Momentum is always conserved in any interaction where no external forces act.

Question 36

Impulse

Answer 36

The change of momentum.

Question 37

Elastic collision

Answer 37

Where both momentum and kinetic energy are conserved.

Question 38

Inelastic collision

Answer 38

Where only momentum is conserved. While kinetic energy is converted into other forms.

Question 39

Work done

Answer 39

The force causing a motion multiplied by the distance travelled in the direction of the force.

Question 40

Power

Answer 40

The rate of energy transfer.

Question 41

Where can you find the Work done if you can't use the formula?

Answer 41

The area under a force-displacement graph.

Question 42

Efficiency

Answer 42

The measure of how efficiently a system transfers energy. Calculated by dividing useful power output by total energy input.

Question 43

Conservation of energy

Answer 43

Energy cannot be created or destroyed, but can be transferred from one form to another.