P10- Force and motion

Question 1

Newton’s second law of motion

Answer 1

Acceleration of an object is…
-Proportional to the resultant force acting on the object
-Inversely proportional to mass of the object

Question 2

Inertia

Answer 2

The tendency of an object to stay at rest or in uniform motion

Question 3

Inertial mass

Answer 3

Ratio of force over acceleration
How difficult it is to change the velocity of an object

Question 4

When does the velocity of an object increase?
When does the velocity of an object decrease?

Answer 4

If resultant force is in the same direction of velocity
If resultant force is in opposite direction of velocity

Question 5

Resultant force if an object falls with no other forces acting on it?

Answer 5

Weight

Question 6

Weight

Answer 6

Force acting on an object due to gravity

Question 7

Mass

Answer 7

Quantity of matter in an object

Question 8

Gravitational field strength and unit

Answer 8

Gravitational force on a 1kg object N/kg

Question 9

Resultant force if an object falls in a fluid?

Answer 9

-Fluid drags on the object due to friction
-Resultant force is its weight minus the drag force

Question 10

Acceleration if an object falls in a fluid

Answer 10

Decreases as it falls, frictional force increases

Question 11

Velocity if an object falls in a fluid

Answer 11

-Reaches constant velocity when frictional force= weight
-Resultant force is 0
-Called terminal velocity

Question 12

2 things braking force depends on

Answer 12

Speed of vehicle
Mass of vehicle

Question 13

Stopping distance is what?

Answer 13

Thinking distance and braking distance

Question 14

Thinking distance

Answer 14

Distance travelled by a vehicle in the time it takes for a driver to react

Question 15

Braking distance

Answer 15

Distance travelled by a vehicle during the time the braking force acts

Question 16

Factors that affect thinking distance and what effect they have?

Answer 16

Tiredness, alcohol, drugs, distractions
Increase thinking distance

Question 17

Factors that affect braking distance and what effect they have?

Answer 17

Speed of car, adverse road conditions, condition of brakes and tyres
Increases braking distance

Question 18

Law of conservation of momentum

Answer 18

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

Question 19

Conservation of momentum equation when two objects travel apart

Answer 19

(mass of A x velocity of A) = -(mass of B x velocity of B)

Question 20

Conservation of momentum when two objects travel apart explained

Answer 20

Minus sign shows momentum of B is in opp direction to A
Both have equal and opp amounts of momentum
Total momentum after=total momentum before

Question 21

Impact time affecting impact force?

Answer 21

The greater the impact time, the more the impact force is reduced

Question 22

Force equation using time, mass, velocity

Answer 22

Force= mass x change in velocity / time

Question 23

When two vehicles collide what 2 things are the same?

Answer 23

The force exerted on each other
Their total momentum

Question 24

Elastic meaning

Answer 24

When an object returns to original shape when forces are removed

Question 25

Hooke’s Law practical

Answer 25

Attach spring and ruler to clamp stand
Use G-clamp to secure clamp stand
Measure original length of spring with ruler
Add one mass to spring, record its length, measure from same point
Calculate extension (new length-original)
Repeat until all masses added to spring

Question 26

Axis for Hooke’s law practical?
Gradient for stiff spring?
Medium stiff?
Soft spring?

Answer 26

X axis- extension
Y axis- force
Steep gradient
Less steep gradient
Shallow gradient

Question 27

Hooke’s law

Answer 27

Force applied to a spring and its extension are directly proportional, as long as its limit of proportionality isn’t exceeded

Question 28

What happens to the force and extension relationship when it is beyond the limit of proportionality?

Answer 28

Extension of spring is no longer proportional to applied force