Impact Force - Revision history

NRJC: /* Equation */

2020-01-05T20:41:36Z

‎Equation

NRJC: /* Equation */

2020-01-05T20:38:56Z

‎Equation

NRJC: /* Example Calculations */

2019-02-17T09:20:30Z

‎Example Calculations

NRJC at 09:20, 17 February 2019

2019-02-17T09:20:04Z

NRJC: /* Equation */

2019-02-16T16:00:41Z

‎Equation

NRJC: /* Equation */

2019-02-16T16:00:23Z

‎Equation

NRJC: /* Key Stage 4 Higher */

2019-02-16T16:00:04Z

‎Key Stage 4 Higher

NRJC at 15:59, 16 February 2019

2019-02-16T15:59:45Z

NRJC: Created page with "==Key Stage 4 Higher== ===Meaning=== An '''impact force''' is the force involved in the collision between two objects. ===About Impact Forces=== : '''Impact forces'''..."

2019-02-16T15:59:05Z

Created page with "==Key Stage 4 Higher== ===Meaning=== An '''impact force''' is the force involved in the collision between two objects. ===About Impact Forces=== : '''Impact forces'''..."

New page

==Key Stage 4 Higher==
===Meaning===
An '''impact force''' is the [[force]] involved in the collision between two [[object]]s.

===About Impact Forces===
: '''Impact forces''' are proportional to the change in [[momentum]] during a [[collision]] and inversely proportional to the [[time]] taken for the [[collision]].
: '''Impact forces''' explain the reason crashing at high [[speed]] is so dangerous and why cars have crumple zones and air bags. They both increase the time taken for the passengers to change [[momentum]] which reduces the [[force]] experienced by them.

===Equation===
''NB: You do not need to remember the equation but you do need to be able to use it.
Combining the two equations:

<math>a=\frac{F}{m}</math>

and

<math>a = \frac{\delta v}{t}<\math>

Gives

<math>\frac{F}{m} = \frac{\delta v}{t}<\math>

<math>F = \frac{m \delta v}{t}<\math>

Where:

<math>F <\math> = The impact [[force]].

<math>m \delta v</math> = The change in [[momentum]].

<math>t<\math> = The time taken for the [[momentum]] to change.

@@ Line 23: / Line 23: @@
 <math>F = \frac{m \Delta v}{t}</math> or <math>F = \frac{mv - mu}{t}</math>
-Where:
+Where
 <math>F </math> = The impact [[force]].

@@ Line 39: / Line 39: @@
 ===Example Calculations===
 {| class="wikitable"
-| style="height:20px; width:200px; text-align:center;" |A car travelling at 20m/s collides with a lamppost and comes to a complete stop in 0.16 seconds. If the passenger has a [[mass]] of 80kg, calculate the [[force]] exerted by the seat belt on the passenger correct to two [[Significant Figures|significant figures]].
+| style="height:20px; width:300px; text-align:center;" |A car travelling at 20m/s collides with a lamppost and comes to a complete stop in 0.16 seconds. If the passenger has a [[mass]] of 80kg, calculate the [[force]] exerted by the seat belt on the passenger correct to two [[Significant Figures|significant figures]].
-| style="height:20px; width:200px; text-align:center;" |During a crash the air bag activates. By the time the car stops the drivers 5kg head is still moving forward with a velocity of 2.4m/s and collides with the airbag. This collision lasts for 0.25 seconds. Calculate the [[force]] between the air bag and the person's head during the collision.
+| style="height:20px; width:300px; text-align:center;" |During a crash the air bag activates. By the time the car stops the drivers 5kg head is still moving forward with a velocity of 2.4m/s and collides with the airbag. This collision lasts for 0.25 seconds. Calculate the [[force]] between the air bag and the person's head during the collision.
 |-
-| style="height:20px; width:200px; text-align:left;" |'''1. State the known quantities'''
+| style="height:20px; width:300px; text-align:left;" |'''1. State the known quantities'''
 Δv = 20m/s
@@ Line 49: / Line 49: @@
 m = 80kg
-| style="height:20px; width:200px; text-align:left;" |'''1. State the known quantities'''
+| style="height:20px; width:300px; text-align:left;" |'''1. State the known quantities'''
 Δv = 2.4m/s
@@ Line 57: / Line 57: @@
 m = 5kg
 |-
-| style="height:20px; width:200px; text-align:left;" |'''2. [[Substitute (Maths)|Substitute]] the numbers into the [[equation]] and [[Solve (Maths)|solve]].'''
+| style="height:20px; width:300px; text-align:left;" |'''2. [[Substitute (Maths)|Substitute]] the numbers into the [[equation]] and [[Solve (Maths)|solve]].'''
 <math>F = \frac{m \Delta v}{t}</math>
@@ Line 66: / Line 66: @@
 <math>F = 10000N</math>
-| style="height:20px; width:200px; text-align:left;" |'''2. [[Substitute (Maths)|Substitute]] the numbers into the [[equation]] and [[Solve (Maths)|solve]].'''
+| style="height:20px; width:300px; text-align:left;" |'''2. [[Substitute (Maths)|Substitute]] the numbers into the [[equation]] and [[Solve (Maths)|solve]].'''
 <math>F = \frac{m \Delta v}{t}</math>

@@ Line 15: / Line 15: @@
 and
-<math>a = \frac{\Delta v}{t}</math>
+<math>a = \frac{\Delta v}{t}</math> or <math>a = \frac{v-u}{t}</math>
 Gives
@@ Line 21: / Line 21: @@
 <math>\frac{F}{m} = \frac{\Delta v}{t}</math>
-<math>F = \frac{m \Delta v}{t}</math>
+<math>F = \frac{m \Delta v}{t}</math> or <math>F = \frac{mv - mu}{t}</math>
 Where:
@@ Line 30: / Line 30: @@
 <math>t</math> = The time taken for the [[momentum]] to change.

@@ Line 21: / Line 21: @@
 <math>\frac{F}{m} = \frac{\Delta v}{t}</math>
-<math>F = \frac{m \delta v}{t}</math>
+<math>F = \frac{m \Delta v}{t}</math>
 Where:
@@ Line 27: / Line 27: @@
 <math>F </math> = The impact [[force]].
-<math>m \delta v</math> = The change in [[momentum]].
+<math>m \Delta v</math> = The change in [[momentum]].
 <math>t</math> = The time taken for the [[momentum]] to change.

@@ Line 15: / Line 15: @@
 and
-<math>a = \frac{\Delta v}{t}<\math>
+<math>a = \frac{\Delta v}{t}</math>
 Gives
-<math>\frac{F}{m} = \frac{\Delta v}{t}<\math>
+<math>\frac{F}{m} = \frac{\Delta v}{t}</math>
-<math>F = \frac{m \delta v}{t}<\math>
+<math>F = \frac{m \delta v}{t}</math>
 Where:

@@ Line 9: / Line 9: @@
 ===Equation===
 ''NB: You do not need to remember the equation but you do need to be able to use it.
-Combining the two equations:
+Combining the two equations
 <math>a = \frac{F}{m}</math>