Paper 2, Topic 5 - Forces

Question 1

What is a scalar quantity?

Answer 1

A quantity with only magnitude, not direction

Question 2

What is a vector quantity?

Answer 2

A quantity with both direction and magnitude

Question 3

How can a vector quantity be drawn and what does it show?

Answer 3

An arrow, length represents magnitude, shows force’s direction

Question 4

What is a force?

Answer 4

A push or pull acting on an object due to interaction with another object

Question 5

Give 4 examples of contact forces

Answer 5

Friction, tension, air resistance, normal reaction

Question 6

Give 3 examples of non-contact forces

Answer 6

Gravitational, electrostatic, magnetic

Question 7

Give 3 examples of vector quantities

Answer 7

Velocity, displacement, force

Question 8

Give 3 examples of scalar quantities

Answer 8

Speed, distance, time

Question 9

What is weight?

Answer 9

Force that acts due to gravity and the object’s mass, measured in Newtons (N)

Question 10

Give the formula for weight

Answer 10

W=mg

Question 11

What is an object’s centre of mass?

Answer 11

The single point where an object’s weight can be considered to act through

Question 12

What piece of equipment can measure an object’s weight?

Answer 12

Newton-meter

Question 13

What does it mean for an object to do work?

Answer 13

Force causes an object to be displaced through a distance

Question 14

What is the equation for work done?

Answer 14

W=Fs

Question 15

What happens when work is done against frictional forces?

Answer 15

Rise in temperature, kinetic energy converted to thermal

Question 16

Why does air resistance slow down a projectile?

Answer 16

Object does work against air resistance, kinetic energy converted to heat

Question 17

State Hooke’s Law

Answer 17

Extension of a spring is directly proportional to the force applied, provided that the limit of proportionality is not exceeded, F=Ke

Question 18

What is inelastic (plastic) deformation?

Answer 18

A deformation which results in the object being permanently stretched, object doesn’t return to its original state

Question 19

What is an alternative name for the turning effect of a force?

Answer 19

Moment

Question 20

State the equation for moments

Answer 20

M = Fd

Question 21

What distance measurement is used when calculating a moment?

Answer 21

The perpendicular distance from the pivot to the line of action of force

Question 22

What happens when an object is in equilibrium?

Answer 22

Clockwise moments = anticlockwise moments

Question 23

What 3 parts make up a lever system?

Answer 23

Load, effort, pivot

Question 24

How can a lever be used as a force multiplier?

Answer 24

If the distance between effort and pivot is greater than the distance between pivot and load, the force applied on the load is greater than the effort force

Question 25

Give an example of when a lever may be used to multiply a force?

Answer 25

Wrench

Question 26

Describe the moment and speed of a larger gear being driven by a smaller gear

Answer 26

The larger gear will rotate more slowly but will produce a larger moment

Question 27

Explain why atmospheric pressure decreases with height

Answer 27

Pressure created by collisions of air molecules, quantity of molecules decreases as height increases, therefore atmospheric pressure decreases with height

Question 28

How does pressure in fluids increase with depth?

Answer 28

As depth increases the mass above increases, force due to mass increases, force has increased whilst area has remained constant so pressure will increase

Question 29

Why does pressure in fluids increase with density?

Answer 29

As density increases the number of particles in a given volume increases, weight of fluid is greater, force from fluid above a certain point is larger, force has increased so pressure increases