Forces

Question 1

What is a scalar quantity?

Answer 1

A quantity that only has magnetude.

Question 2

What is a vector quantity?

Answer 2

A quantity that has magnitude and direction.

Question 3

What is typical driving speed (on a county road)?

Answer 3

80km/h

Question 4

What is typical running speed?

Answer 4

3m/s

Question 5

What is typical cycling speed?

Answer 5

6m/s

Question 6

What is instantaneous speed?

Answer 6

The speed at a given point.

Question 7

How do you find the speed on a distance time graph?

Answer 7

The gradient

Question 8

What is the definition of constant speed?

Answer 8

When an object moves the same distance in equal intervals of time.

Question 9

Why is circular motion at a constant speed accelerating?

Answer 9

• The object is changing direction
• So its volocity changes
• So it is accelerating

Question 10

What is the force that causes circular motion?

Answer 10

A centripetal force, acting towards the cenre of the circle

Question 11

How do you calculate distance on a velocity time graph?

Answer 11

The area under the graph.

Question 12

How does normal reaction force work?

Answer 12

• Weight pushes down on particles
• This compresses the bonds between them
• The bonds push back against the weight

Question 13

What is Newton’s third law?

Answer 13

If object A exerts a force on object B, then object B exerts an equal and opposite force on object A.

Question 14

What is Newton’s first law?

Answer 14

An object at rest stays at rest and an object in motion stays in motion with the same speed and direction unless acted on by a resultant force.

Question 15

What is inertia?

Answer 15

The resistance an object has to a change in its motion.

Question 16

How does mass effect inertia?

Answer 16

The larger the mass - the larger the inertia

Question 17

What is Newton’s second law?

Answer 17

Force = Mass x Acceleration

Question 18

What is the relationship mass and acceleration?

Answer 18

They are inversely proportional

Question 19

What is inertial mass?

Answer 19

A measure of how difficult it is to change the velocity of an object.

Question 20

What is the center of mass of an object?

Answer 20

The point at which the weight of the object is considered to act.

Question 21

What is gravity?

Answer 21

The force that causes anything with mass to be attracted to anything else with mass.

Question 22

What is the value of acceleration due to gravity?

Answer 22

9.8m/s²

Question 23

What is terminal velocity?

Answer 23

The maximum constant velocity of an object.

Question 24

What is the relationship between force, and extension on a spring?

Answer 24

They are directly proportional

Question 25

What is the spring constant?

Answer 25

A measure of how difficult it is to stretch/compress a spring.

Question 26

What is the limit of elasticity?

Answer 26

The point where a larger force will result in the material loosing its elasticity.

Question 27

What happens o the energy stored in a spring when it is inelastically deformed?

Answer 27

The elastic potential energy stored in it is no longer equal to the work done on it.

Question 28

How do you calculate stopping distance?

Answer 28

Thinking distance + breaking distance

Question 29

What is thinking distance?

Answer 29

The distance traveled while the driver thinks about breaking. Influenced by vehicle speed, and drivers reaction time.

Question 30

What is breaking distance?

Answer 30

The distance traveled while the breaks are applied. Influeced by vehicle speed, mass, condition of vehicle, and condition of the road.

Question 31

What is momentum?

Answer 31

The product of an objects mass and it's velocity.

Question 32

What is the principle of conservation of momentum?

Answer 32

In a closed system , the total momentum before an event s equal to the total momentum after the event.

Question 33

What is an explosion

Answer 33

Where objects begin touching each other at rest, and then move apart.

Question 34

What happens in perfectly inelastic collisions?

Answer 34

The masses stick together when they collide, creating a larger mass with a different volocity.

Question 35

What happens in elastic collisions?

Answer 35

The masses bounce off each other and move in different directions.

Question 36

How can the force of a collision be reduced?

Answer 36

By increasing the impact time.

Question 37

What is a moment?

Answer 37

The turning effect produced by a force.

Question 38

What is the unit of moments?

Answer 38

Newton meters (Nm)

Question 39

What are the 2 ways that levers can be used?

Answer 39

- Force multipliers - Distance multipliers

Question 40

How do you find the ratio of moments for gears?

Answer 40

Ratio of moments = Ration of teeth = ratio of radii

Question 41

Why does pressure increase with depth in fluids?

Answer 41

- More particle are above it - More weight acting downwards - Greater force acting over the same area - So a greater pressure

Question 42

Why do objects experience upthrust?

Answer 42

The bottom of the object has a greater pressure that the top, so it is pushed upwards.

Question 43

When will an object float?

Answer 43

When upthrust is equal in size to the weight of the fluid that the object displaces.

Question 44

Why does atmospheric pressure decrease with height?

Answer 44

- The air becomes less dense - There are fewer molecules above a surface - Fewer collisions with the surface - So there is less pressure