Topic 3.3: Acceleration

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• Middelbare school
• havo
• Leerjaar 2

Topic 3.3 

Acceleration

The unit for force is:

1. N
2. F
3. kg
4. Nm

There are 2 Forces working on an object. When is the resulting force zero?

1. When the forces are working in the same direction
2. When the forces are opposites
3. When the forces have te same magnitude
4. When they are the same magnitude and opposite to each other

Dog A is pulling with a force of 60 N and dog B is pulling in the opposite direction with a force of 75 N
What is the resultant force?

1. 15 Newton to dog A
2. 75 Newton to dog B
3. 60 Newton to dog A
4. 15 Newton to dog B

The symbol for speed is

1. s
2. v
3. m/s
4. km/h

3.2 : Speed

The speed can be given in 2 different units

m/s  (meters per second)

km/h (kilometers per hour)

recap 3.2: Speed

Speed (velocity) is the distance you travel in a given time

v for velocity in [m/s or km/h]

s for distance in [m or km]

t for time in [s or h(our)]

time can be calculated with the following formula

1. t= v/s time = speed / distance
2. t = s/v time = distance /speed
3. t = s x v time = distance * speed
4. t = s + v time = distance + speed

Convert 100 km/h to m/s?

1. 27,8 m/s
2. 360 m/s
3. 103,6 m/s
4. 96,4 m/s

3.3 Acceleration

Learning goals

1. You can describe the concept of acceleration and understand which measurements and units are necessary to calculate it

2. i can create and interpret v,t-diagrams relating to an object's change in motion

3. i can use an object's resultant force to determine what type of motion it has

3.3 Acceleration

Acceleration is change in speed, so speeding up or slowing down, measured in meters per second squared (m/s2).

acceleration is an increase in speed

a is a positive number

a decrease in speed is called decelaration

a is a negative number

Johanie is at a traffic light. As soon as it hits green, he starts to speed up on his bike. He accelerates with 5 m/s2.
What is his speed after 4 seconds?

1. 9 m/s
2. 1 m/s
3. 20 m/s
4. 1,25 m/s

convert 18 m/s to km/h

1. 14,4 km/h
2. 65 km/h
3. 5 km/h
4. 21,6 km/h

3.3: acceleration

3.3: acceleration

acceleration is positive when speed increases

delta v = v(final) - v(initial)

delta v = 20 - 0 = 20 m/s (so it is positive)

a = 20/5 = 4 m/s2 (also positive)

3.3: acceleration

acceleration is negative when speed decreases

delta v = v(final) - v(initial)

delta v = 0 - 20 = -20 m/s (so it is negative)

a = -20/5 = -4 m/s2 (also negative)

The mass of Mohamed is 45 kg. What is his gravitational force, Fg

1. 350 N
2. 45 N
3. 441 N
4. 882 N

How far did this object travel after 16 seconds?

1. 500 km
2. 1000 km
3. 0 km
4. 300 km

I want to draw a force with a magnitude of 600 N.
The scale must be 1 cm = 60 N
How large should the arrow (vector) be?

1. 2 cm
2. 5 cm
3. 10 cm
4. 12 cm

3.3 acceleration

Moving at a constant speed gives me these 2 graphs

Notice that the first is an s,t-diagram,

The second one is a v,t-diagram

3.3 acceleration

Moving at a constant acceleration gives me these 2 graphs

Notice that the first is an s,t-diagram,

The second one is a v,t-diagram

3.3 acceleration

Moving at a constant negative acceleration gives me these 2 graphs

Notice that the first is an s,t-diagram,

The second one is a v,t-diagram

A car is accelerating for 8 seconds, increasing by 20 m/s every second. What is his final speed?

1. 28 m/s
2. 160 m/s
3. 2,5 m/s
4. 12 m/s

Homework

make exercises 22,23 and 24

Have a good time in Bath

3.3 acceleration

resultant force 

The result of multiple forces

same direction ? add them up

opposite direction? subtract them

3.3 Acceleration

3.3 Acceleration

If the resultant force is 0 N, the object is not accelerating

The speed is constant

standing still is also a constant speed (0 m/s)

3.3 Acceleration

If the resultant force is + N, the object will accelerate

(+ means it is in the same direction as the movement)

3.3 Acceleration

If the resultant force is - N, the object will decelerate

(- means the resultant force is opposite to the direction of movement)

What kind of movement will happen in this situation?

1. constant speed to the left
2. constant speed to the right
3. acceleration to the left
4. acceleration to the right

What kind of movement wil happen here

1. constant speed downwards
2. constant speed upwards
3. deceleration downwards
4. deceleration upwards

On an object the following forces are acting:
50 N to the right
20 N upwards
75 N to the left
20 N downwards
What type of motion will happen?

1. acceleration upwards
2. acceleration to the right
3. acceleration downwards
4. acceleration to the left

3.3 Acceleration

Learning goals

1. You can describe the concept of acceleration and understand which measurements and units are necessary to calculate it

2. i can create and interpret v,t-diagrams relating to an object's change in motion

3. i can use an object's resultant force to determine what type of motion it has