Transcript 2.2 Resultant force

2.2 Resultant force
1.
2.
3.
4.
5.
6.
7.
8.
6+5=
15 – 10 =
3a + 5a =
100N – 50N =
40 – 40 =
100N – 200N =
50kN – 25kN =
1kN – 500N =
06 April 2016
Try
these
sums
2.2 Resultant force
1.
2.
3.
4.
5.
6.
7.
8.
06 April 2016
6 + 5 = 11
15 – 10 = 5
3a + 5a = 8a
100N – 50N = 50N
40 – 40 = 0
100N – 200N = -100N
50kN – 25kN = 25kN
1kN – 500N = 500N (1k = 1000)
2.2 Resultant force
06 April 2016
• What is a resultant force?
• What happens if the resultant force is zero?
• What happens if there is a resultant force?
Voyager 2 was launched in
1974. Since then it has had
no main rocket engine to
power it. The spacecraft is
now at the edge of the
Solar System travelling at
60 000 mph!
How can it keep going?
Resultant force
• A single force used to represent all the
forces on an object.
Resultant
10N
20N
=
10N
What is the missing resultant force?
10N
=
20N
?
Newton’s 1st Law of motion
When the resultant force on an object is
zero:
•An object stays still
•Has a constant velocity
Explain how a skater carries on
moving with no effort on ice.
Which force is zero on ice?
When the resultant force is not zero the object
changes its velocity.
What happens when the:
1. Weight is more than the Lift force?
2. Lift is more than the Weight?
3. Weight equals the Lift?
Accidents
Draw a diagram to show the lorry hitting the car.
Include:
1. The direction the lorry was travelling
2. The force needed to stop the lorry
3. The force on the car.
Investigation
When the resultant force on an object is zero:
•An object stays still
•Has a constant velocity
Use a trolley to look at Newton’s 1st Law.
• How can you get the trolley to move at a
constant speed?
• Which forces must be balanced for this
to happen?
books
Trolley
Key Points
Copy this table
Start
Resultant Force
Effect on object
1
At rest
Zero
Stays at rest
2
Moving
Zero
3
Moving
Velocity stays
the same
Accelerates
4
Moving
In direction of
movement.
Against direction Decelerates
of movement