[Part 2]- P10- Forces and motion 🚙

Question 1

What is the stopping distance ?

Answer 1

• the stopping distance of a vehicle is:
• the sum of the distance the vehicle travels during the reaction time, [thinking distance] and the distance it travels under the braking force [braking distance]

Question 2

What is the thinking distance ?

Hint: vehicle

Answer 2

• the thinking distance, is the distance travelled by the vehicle during the driver’s reaction time
• [hint- thinks link to reaction]

Question 3

What is the breaking distance ?

Hint: applies

Answer 3

• the breaking distance, is the distance the vehicle travels from when the driver applies the brakes, to when the car stops

Question 4

• Fill in the gaps: the _______ the speed of the vehicle, the greater the stopping ________ [assuming that the same braking force is applied]

Answer 4

• the greater the speed of the vehicle, the greater the stopping distance [assuming that the same braking force is applied]

Question 5

What is the typical range for a person’s reaction time ?

Answer 5

• the typical range for a person’s reaction time is:
• bewteen 0.2 and 0.9 seconds

Question 6

How can a person’s reaction time be measured ?

Answer 6

• we can measure a person’s reaction time:
• by using the ruler drop test

Question 7

What factors affects thinking distance ?

Answer 7

• reaction time- the longer a person’s reaction time, the longer the thinking distance
• speed- the faster a person travels, the further a person will travel, during the time it takes for them to react

Question 8

What can the reaction time of a driver, be affected by ?

Hint: in the car

Answer 8

• reaction time can be affected by:
• alcohol and drugs
• distractions in the car
• and if a driver is tired

Question 9

What factors can braking distance be affected by ?

Hint: conditions

Answer 9

• wet or icy conditions
• the conditions of the tyres
• the conditions of the brakes

Question 10

How can wet or icy conditions, affect the braking distance ?

Answer 10

• wet or icy conditions- this can increase the breaking distance.
• this is because, wet and icy conditions reduce the friction bewteen the tyres, and the road

Question 11

How can the conditions of the tyres, affect the braking distance ?

Answer 11

• the conditions of the tyres- if a car has worn tyres, the braking distance will also increase
• this is because, worn tyres reduces the friction between the tyres and the road

Question 12

• Fill in the gaps: because kinetic energy depends on the velocity _______ if the velocity of a car is doubled, the kinetic ______ of a car quadruples.

Answer 12

• because kinetic energy depends on the velocity squared if the velocity of a car is doubled, the kinetic energy of a car quadruples.

Question 13

If a driver is going at a fast speed, what happens ?

Answer 13

• if a driver is driving at a fast speed, they will have to apply a large braking force.
• this is because, the greater the speed, the greater the breaking force needed to stop the car [in a certain distance]

Question 14

What is momentum ?

Answer 14

• momentum, can be defined as ‘mass in motion.’
• [this is because, all objects have mass, so if an object is moving, then it has momentum - because it has its mass in motion]

Question 15

What objects have momentum ?

Answer 15

• all moving objects have momentum
• ; if an object is not moving, the object’s momentum is zero [as it has no momentum]

Question 16

What is the conservation of momentum ?

Answer 16

• the conservation of momentum, states that in a closed system the total momentum before an event, is equal to the total momentum after an event

Question 17

How can a canon, be an example of the conservation of momentum ?

Hint: velocity

Answer 17

• if a canon contains a canon ball, before the canon moves, the canon and cannonball are not moving, so have no momentum
• ; when the canon fires, the cannonball is moving at a large velocity meaning it has momentum in the forwards direction [as it also has mass].
• ; the cannon also recoils [moves backwards] so the cannon has momentum in the backwards direction [cancelling out the ball’s momentum]- meaning momentum is conserved, as the total momentum is zero

Question 18

What is elastic deformation ?

Answer 18

• an elastic deformation, is when a material is able to regain its shape, after it has been squashed or stretched

Question 19

What is inelastic deformation ?

Hint: why ?

Answer 19

• inelastic deformation, is when a material is deformed and dosen’t regain its shape after being squashed or stretched because, the forces applied are unbalanced

Question 20

Fill in the gaps: when an elastic object is stretched or compressed, a force is used to __ work

Answer 20

• when an elastic object is stretched or compressed, a force is used to do work

Question 21

When is work done equal to elastic potential energy ?

Answer 21

• when an elastic object is stretched or compressed, elastic potential energy is stored in the object
• this means if the object is not inelastically deformed, the work done is equal to the elastic potential energy of the object