Mechanics

Question 1

Define speed

Answer 1

distance travelled per unit time

Question 2

vector

Answer 2

a quantity of both direction and magnitude

Question 3

scalar

Answer 3

scalar quantities have magnitudes only

Question 4

velocity

Answer 4

change in displacement per unit time

Question 5

acceleration

Answer 5

change in velocity per unit time

Question 6

The Newton

Answer 6

the force that causes a mass of 1kg to accelerate at 1m/s SQUARED

Question 7

moment

Answer 7

force x perpendicular distance from the pivot

The turning effect caused by a force on a pivoted object.

Question 8

principle of moments

Answer 8

for rotational equilibrium, the sum of the clockwise moments about a pivot equals the sum of the anticlockwise moments about the pivot

Question 9

torque of a couple

Answer 9

one of the forces × perpendicular distance between the forces

(The product of two forces in opposite directions, and equal distance from the pivot)

Question 10

an object in equilibrium

Answer 10

sum of all forces acting on the object is zero;

clockwise moments on the object equal anticlockwise moments about the pivot

Question 11

centre of gravity

Answer 11

point where all the weight (or mass) of a body appears to act

Question 12

density

Answer 12

mass / volume

Question 13

pressure

Answer 13

force normal to surface / area

Question 14

work done

Answer 14

force × distance moved in the direction of the force

Question 15

the Joule

Answer 15

the work done when 1 Newton acts over a distance of 1 metre

Question 16

power

Answer 16

work done / time OR the rate at which work is done/energy is transferred

(1 watt = 1 joule / second)

Question 17

thinking distance

Answer 17

distance travelled from when driver detects hazard to when driver applies brakes

Question 18

braking distance

Answer 18

distance travelled after the brakes have been applied until vehicle stops

Question 19

gravitational potential energy

Answer 19

mass × gravitational field strength × height

Question 20

kinetic energy

Answer 20

½ × mass × speed2

Question 21

Average speed

Answer 21

The overall distance travelled divided by time taken

Question 22

Instantaneous speed

Answer 22

The speed of an object at a particular instant in time

Question 23

Conservation of energy

Answer 23

A principle stating that the total energy of an isolated system remains constant, regardless of changes within the system.

Question 24

Displacement

Answer 24

The distance travelled in a particular direction from the origin.