Topic 4 - Mechanics

Question 1

Acceleration

Answer 1

Change of velocity per unit time.

Question 2

Acceleration of free fall

Answer 2

Acceleration of an object acted on only by the force of gravity.

Question 3

Braking distance

Answer 3

The distance travelled by a vehicle in the time taken to stop it.

Question 4

Centre of Mass

Answer 4

The centre of mass of a body is the point through which a single force on the body has no turning effect.

Question 5

Couple

Answer 5

Pair of equal and opposite forces acting on a body but not along the same line.

Question 6

Displacement

Answer 6

Distance in a given direction

Question 7

Drag force

Answer 7

The force of fluid resistance on a object moving through the fluid.

Question 8

Efficiency

Answer 8

The ratio of useful energy transferred (or the useful work done) by a machine or device to the energy supplied to it. The ratio of the machines outward power to its input power.

Question 9

Effort

Answer 9

The force applied to a machine to make it move.

Question 10

Equilibrium

Answer 10

State of an object when at rest or in uniform motion.

Question 11

Force

Answer 11

Any interaction that can change the velocity of an object. measured in Newtons.

Question 12

Free body force diagram

Answer 12

A diagram of an object showing only the forces acting on the object.

Question 13

Friction

Answer 13

Force opposing the motion of a surface that moves or tries to move across another surface.

Question 14

Gravitational field strength

Answer 14

Force of gravity per unit mass on a small object.

Question 15

Inertia

Answer 15

Resistance of an object to change of its motion.

Question 16

Kinetic energy

Answer 16

The energy of an object due to its motion.

Question 17

Load

Answer 17

The force to be overcome by a machine when it shifts or raises an object.

Question 18

Mass

Answer 18

Measure of the inertia or resistance to change of motion of an object.

Question 19

Moment of a force about a point

Answer 19

Force x perpendicular distance from the line of action of the force to the point.

Question 20

Momentum

Answer 20

Mass x velocity

Question 21

Motive force

Answer 21

The force that drives a vehicle.

Question 22

Newton’s first law of motion

Answer 22

An object remains at rest or in uniform motion unless acted on by a resultant force.

Question 23

Newton’s second law of motion

Answer 23

The rate of change of momentum of an object is proportional to the resultant force (F) on it. Newton’s second law may be written as F = change in (ma)/ change in time. For constant mass, this equation becomes F = ma.

Question 24

Potential energy

Answer 24

The energy of an object due to its position.

Question 25

Power

Answer 25

Rate of transfer of energy.

Question 26

Pressure

Answer 26

Force per unit area acting on a surface perpendicular to the surface.

Question 27

Principle of conservation of energy.

Answer 27

Energy cannot be created or destroyed.

Question 28

Principle of moments

Answer 28

For an object in equilibrium, the sum of the clockwise moments about any point = the sum of the anti-clockwise moments about that point.

Question 29

Projectile

Answer 29

A projected object in motion acted on only by the force of gravity.

Question 30

Scalar

Answer 30

A physical quantity with magnitude only.

Question 31

Speed

Answer 31

Change of distance per unit time. Measured in m/s

Question 32

Stopping distance

Answer 32

Thinking distance + braking distance

Question 33

Terminal speed

Answer 33

The maximum speed reached by an object when the drag on it is equal and opposite to the force causing the motion of the object.

Question 34

Thinking distance

Answer 34

The distance travelled by a vehicle in the time it takes the driver to react.

Question 35

Useful energy

Answer 35

Energy transferred to where it is wanted when it is wanted.

Question 36

Vector

Answer 36

A physical quantity with a magnitude and direction.

Question 37

Velocity

Answer 37

Change in displacement per unit time.

Question 38

Weight

Answer 38

The force of gravity acting on an object.

Question 39

Work

Answer 39

Force x distance moved in the direction of the force.