Topic 3.3: Acceleration

• Science
• Middelbare school
• havo
• Leerjaar 2

Topic 4 

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

4 : Velocity

The speed can be given in 2 different units

m/s  (meters per second)

km/h (kilometers per hour)

recap 4.1: 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

4.2 Force, Mass and 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

4.2 Force, Mass and 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

Tugra 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

4.2 Force, Mass and Acceleration

4.2 Force, Mass and 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)

4.2 Force, Mass and 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 Siem 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

4.2 Force, Mass and 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

4.2 Force, Mass and 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

4.2 Force, Mass and 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

4.2 Force, Mass and Acceleration

resultant force 

The result of multiple forces

same direction ? add them up

opposite direction? subtract them

4.2 Force, Mass and Acceleration

4.2 Force, Mass and 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)

4.2 Force, Mass and Acceleration

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

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

4.2 Force, Mass and Acceleration

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

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

4.2 Force, Mass and Acceleration

F = m.a

Force in N

mass in kg

a in m/s^2

How can we calculate mass when knowing acceleration and force?

1. m = F.a
2. m = F/a
3. m = F + a
4. m = a/F

What kind of movement wil happen here

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

4.2 Force, Mass and 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

|What will the formula for distance be when we know work and force?

1. W = f/s
2. s= W/F
3. s = F/W
4. W = F+s

What formulas from this chapter do you remember?

a carengine has to do work to get it to move. If the resultant force on the car is 500 N, how much work must be done to get it to go 250 m?

1. 2 J
2. 125000 J
3. 750 J
4. 0,5 J

F=m x a

F = m x g

W = F x s

a = v/t

V=s/t

E= P x t

Work

Resultant force

Gravitiational force

acceleration

Velocity

Energy