Then write Wednesday and answer the following questions Describe the force that pulls an object down What are three ways to accelerate change velocity If I roll a ball down the road why does it eventually stop ID: 912429
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Slide1
Bell Work 8/19/2020
On a sheet of notebook paper, write at the top “Bell Work”
Then write “Wednesday” and answer the following questions.
Describe the force that pulls an object down.
What are three ways to accelerate (change velocity)?
If I roll a ball down the road, why does it eventually stop?
Slide2Bell Work 8/19/2020
On a sheet of notebook paper, write at the top “Bell Work”
Then write “Wednesday” and answer the following questions.
Describe the force that pulls an object down.What are three ways to accelerate (change velocity)?If I roll a ball down the road, why does it eventually stop?
Gravity pulls an object down.
Speed up, Slow down, or Change direction
Friction between the ball and the road slows it down and causes it to stop.
Slide3Forces
Nature of Forces
What is Acceleration?
Acceleration is the rate at which velocity (speed and direction) changes3 ways to accelerate:Speed up (positive acceleration)Slow down (negative acceleration)Change direction (neutral acceleration)
Slide4Forces
To calculate acceleration,
Use the unit: m/s
2Example:A roller coaster’s velocity at the top of a hill is 10 m/s. Two seconds later it reaches the bottom of the hill with a velocity of 26 m/s. What was the acceleration of the coaster?Acceleration =
(Final speed – Initial Speed)
Time
Slide5Forces
To calculate acceleration,
Use the unit: m/s
2Example:A roller coaster’s velocity at the top of a hill is 10 m/s. Two seconds later it reaches the bottom of the hill with a velocity of 26 m/s. What was the acceleration of the coaster?Acceleration =
(Final speed – Initial Speed)
Timea =
(26 m/s – 10 m/s)
2 s
=
16 m/s
2 s
=
8 m/s/s or
m/s
2
Slide6Bell work 8/21/20
Get out your bell work paper.
Write “Friday” and answer the following questions.
Which of these statements are true?When you press on the gas, the car accelerates. When you press on the brake, the car accelerates.
When you change lanes, the car accelerates.Explain your answer to question #1.
Describe the force it would take for the 8th graders to win a tug of war against the 7
th
graders.
Slide7Bell work 8/21/20
Get out your bell work paper.
Write “Friday” and answer the following questions.
Which of these statements are true?When you press on the gas, the car accelerates. When you press on the brake, the car accelerates.
When you change lanes, the car accelerates.Explain your answer to question #1.
Describe the force it would take for the 8th graders to win a tug of war against the 7
th
graders.
Acceleration depends on velocity and direction.
(+)
(-)
(neutral)
More force than the 7
th
graders
Slide8How are Forces Described?
A force is a push or pull measured in Newtons (N).
Represented using an arrow
The head of the arrow is the direction.The length of the arrow is the strength.
Slide9Bell Work 8/24/2020
On a sheet of notebook paper, write at the top “Bell Work”
Then write “Monday” and answer the following questions.
Describe a force.Describe the two forces that are working on your desk seat right now.
Draw a diagram of this.
Slide10Bell Work 8/24/2020
On a sheet of notebook paper, write at the top “Bell Work”
Then write “Monday” and answer the following questions.
Describe a force.Describe the two forces that are working on your desk seat right now.
Draw a diagram of this.A push or pull
Gravity and your weight is pushing down on the seat. The seat is pushing back so that it is balanced.
Slide11How Do Forces Affect Motion?
Net force is the combination of all forces on an object.
It determines the motion!
If net force is zero, there is no motion; it is balanced. (sitting in chair)If net force is not zero, it will move in the direction of the largest force; it is unbalanced. (driving a car)
Slide12To determine net force, add or subtract all the net forces acting on an object.
If the forces are going in the same direction, add.
If the forces are going in opposite directions, subtract.
1.2.
Slide13To determine net force, add or subtract all the net forces acting on an object.
If the forces are going in the same direction, add.
If the forces are going in opposite directions, subtract.
1.2.
= 0 N
No motion balanced
= 100 N
motion unbalanced