Topic P5-Forces

Question 1

What is a vector quantity and give two examples?

Answer 1

Magnitude and direction
Force and velocity

Question 2

What is a scaler quantity and give two examples?

Answer 2

Magnitude
Speed and distance

Question 3

What are three examples of contact forces?

Answer 3

Friction, air resistance, pushing

Question 4

What are three examples of non-contact forces?

Answer 4

Magnetic, gravitational and electrostatic

Question 5

What is the difference between mass and weight?

Answer 5

Mass is the amount of stuff in an object. Weight is the force acting on an object due to gravity.

Question 6

What is the equation that includes GFS, weight and mass?

Answer 6

Weight (N) = Mass (kg) x GFS (N/Kg)

Question 7

Is weight and mass directly proportional?

Answer 7

Yes

Question 8

What is the resultant force?

Answer 8

When two or more forces act on an object, the resultant force can be found by adding up the individual forces.

Question 9

What is the equation that includes distance, work done and force?

Answer 9

Work done(J)=force(N) x distance(m)

Question 10

What is equilibrium?

Answer 10

When all forces acting on an object combine to give a resultant force of zero

Question 11

What is the difference with elastically deformed and inelastically deformed?

Answer 11

Elastically can go back to its original shape and length, whereas inelastically can’t after the force has been removed

Question 12

What is the equation that includes spring constant, force and extension?

Answer 12

Force(N)= spring constant(N/m) x extension(m)

Question 13

What are four methods to investigate the link between force and extension in a spring?

Answer 13

1) Measure the natural length of the spring with a millimetre ruler clamped to the stand
2)Add a mass to the spring and allow it to come to rest, record the mass and measure the new length of the spring
3)Repeat this process, until you have enough measurements
4)Plot a force extension graph of your results
5) The extension is the change in length

Question 14

What is the equation that includes spring constant, elastic potential energy and extension?

Answer 14

Elastic potential energy(J)=1/2 X spring constant(N/m) X Extension(m)

Question 15

What is displacement?

Answer 15

A vector quantity, it measures the distance and direction in a straight line from an objects starting point to its finishing point.

Question 16

What is velocity?

Answer 16

Speed in a given direction e.g 30mph north

Question 17

What is the equation that has speed, distance travelled and time?

Answer 17

Distance(m) = speed(m/s) X time(s)

Question 18

What is acceleration?

Answer 18

The change in velocity in a certain amount of time

Question 19

What is the equation that has change in velocity, acceleration and time?

Answer 19

Acceleration(m/s2) = Change in velocity(m/s) / Time(s)

Question 20

On a distance-time graph what does a straight uphill section mean?

Answer 20

Travelling at a steady speed

Question 21

On velocity-time graph what does a flat section represent?

Answer 21

Travelling at a steady speed

Question 22

How can you reduce friction between surfaces?

Answer 22

By using a lubricant (usually liquid)

Question 23

When does an object reach a terminal velocity?

Answer 23

When the frictional force is equal to the accelerating force

Question 24

Do objects with a large surface area have a lower or higher terminal velocity?

Answer 24

Lower terminal velocity

Question 25

What are the five methods to investigate motion?

Answer 25

1) connect the trolley with the piece of card to a piece of string that goes over a pulley and is connected on the other side to a hook. 2) mark a starting line on the table the trolley is on, so that it always travels the same distance to the light gate. 3) place the trolley on the starting line, holding the hook so the string is taut, and release it. 4) record the acceleration measured by the light gate. 5) repeat this twice more to get an average acceleration.

Question 26

What are the four steps of the reaction times practical?

Answer 26

1) Person being tested sits with their arm resting on the edge of a table. Make sure that the zero and the ruler are level with a thumb and finger, then let go without giving any warning. 2) Person being tested should try to catch the ruler as quickly as they can. 3) Reaction time is measured by the number on the ruler where it’s caught. The further down the ruler is caught, the slower their reaction time. 4) Repeat the test several times and calculate the mean distance that the ruler fell. The person being tested should have a caffeinated drink after 10 minutes, repeat steps 1 to 5.

Question 27

What is Newton’s First Law?

Answer 27

A resultant force is needed to make something start moving, speed up or slow down

Question 28

What is the equation that includes acceleration, resultant force and mass for Newton’s Second Law?

Answer 28

Resultant force(N)= Mass(kg) x Acceleration(m/s^2)

Question 29

Is acceleration inversely or directly proportional to the resultant force?

Answer 29

Directly proportional

Question 30

Is acceleration inversely or directly proportional to mass?

Answer 30

Inversely proportional

Question 31

What is Newton’s Third Law?

Answer 31

When two objects interact, the forces they exert on each other are equal and opposite

Question 32

What is Newton’s Second Law?

Answer 32

The larger the resultant force acting on an object, the more the object accelerates

Question 33

How do you work out the stopping distance of a vehicle?

Answer 33

Stopping distance= Thinking distance + Breaking distance

Question 34

What is thinking distance affected by?

Answer 34

Speed and reaction time

Question 35

What factors affect braking distance?

Answer 35

Speed, weather, road surface, condition of tyres and condition of breaks