Mechanics

Question 1

Scalar quantity

Answer 1

A quantity that has only magnitude

Question 2

Vector quantity

Answer 2

A quantity that has magnitude as well as direction

Question 3

Is acceleration vector or scalar

Answer 3

Vector

Question 4

Is mass scalar or vector

Answer 4

Scalar

Question 5

Difference between mass and weight

Answer 5

Mass is scalar and is not dependent on the gravity acting upon it. Weight is a vector and depends on the gravitational field strength
W = mg

Question 6

Equilibirum

Answer 6

¬ Sum of anticlockwise moments = sum of clockwise moments
¬ Stationary or moving at a constant velocity

Question 7

How can forces acting on an object be shown in equilibrium

Answer 7

¬ Adding the horizontal and vertical components of the forces acting on it, showing they equal zero
¬ Or is there are 3 forces acting on it you can draw a scale diagram, if the scale diagram forms a closed triangle, then the object is in equilibrium

Question 8

What is a moment

Answer 8

A turning force : force multiplied by the perpendicular distance from the point to the line of action of the force

Question 9

Couple

Answer 9

A pair of equal and opposite coplanar forces

Question 10

Centre of mass

Answer 10

The point through which all the mass of an object acts, for a uniform object the centre of mass is the centre of the object

Question 11

Velocity

Answer 11

The change in displacement per unit time
Can be found by measuring the gradient of a tangent to a displacement time graph

Question 12

Area under a velocity / acceleration time graph

Answer 12

The displacement travelled and the velocity respectively

Question 13

A ball is projected off of a wall at 6m/s how does its horizontal velocity change from its launch until it hits the ground

Answer 13

The horizontal velocity remains the same as there is no acceleration in that direction

Question 14

Vertical acceleration

Answer 14

The vertical acceleration is equal to the gravitational field strength

Question 15

Terminal velocity

Answer 15

When forces acting on h falling object become balanced, the acceleration becomes zero and the object is moving at max velocity

Question 16

Friction

Answer 16

A resistance to motion between an object and a surface or an object moving through a fluid. Friction is a force that acts in the opposite direction to the movement

Question 17

Newton’s third law

Answer 17

Every force has an equal and opposite reaction

Question 18

Newton’s second law

Answer 18

F=ma
Where mass is constant, F is the force applied and a is acceleration

Question 19

Newton’s first law

Answer 19

An object stays moving at a constant velocity until a force acts upon it

Question 20

Difference between elastic and inelastic collisions

Answer 20

Elastic = kinetic energy before is equal to the kinetic energy afterwards
Inelastic = kinetic energy at the end is not equal to the kinetic energy at the start

Question 21

Momentum equation

Answer 21

momentum = mass x velocity

Question 22

Is linear momentum only conserved in elastic collisions?

Answer 22

No, linear momentum is always conserved

Question 23

Force definition

Answer 23

Rate of change of momentum

Question 24

Impulse definition

Answer 24

Change in momentum
F(change in)t = (change in)mv

Question 25

Area under force time graph

Answer 25

Impulse

Question 26

Fs cos(0) = ?

Answer 26

The work done / energy transferred

Question 27

What is rate of work done equal to

Answer 27

power

Question 28

What is efficiency

Answer 28

Useful output power / input power

Question 29

Principle of conservation of energy

Answer 29

Energy cannot be created or destroyed, only transferred into other forms of energy
Therefore the total every in a closed system will always remain the same

Question 30

What is lift

Answer 30

An upward force which acts on objects travelling in a fluid, it is caused by the object creating a change in direction of fluid flow and acts perpendicular to the direction of fluid flow