Changes in Force and Motion

If mass increases, what must happen to the force in order to achieve the same change in motion?

Answer explanation

The greater the mass of the object, the greater the force needed to achieve the same change in motion.

Tags

NGSS.MS-PS2-2

A boulder sits at rest on top of a mountain. What conclusion can be made about the forces acting on the boulder?

Answer explanation

The forces acting on the boulder are balanced (net force equals zero).

Tags

NGSS.MS-PS2-4

A diagram of forces being applied to a box by four people is illustrated below. If the net force acting on the box is 10N to the right, what is the magnitude of the force applied by the boy pulling to the left?

Answer explanation

14 N

Tags

NGSS.MS-PS2-1

NGSS.MS-PS2-2

Juan and Jose are having an argument about their science book. Juan says that since the book is sitting still, there are no forces acting on it. Jose says there are forces acting on the book. Which student is correct? Explain why.

Answer explanation

Jose is correct because gravity is a force acting on all objects on Earth. However, the forces are balanced so the book is not moving (the net force on the book is zero).

Tags

NGSS.MS-PS2-2

NGSS.MS-PS2-5

What can cause a change in an object’s motion?

Answer explanation

The change in an object’s motion depends on the sum of the forces on the object and the mass of the object.

Tags

NGSS.MS-PS2-1

NGSS.MS-PS2-2

The illustration shows the forces in Newtons (N) acting on three different blocks. Which blocks will experience a change in motion, or acceleration?

• Blocks 1 and 2

• Blocks 2 and 3

• Blocks 1 and 3

• Blocks 1, 2, and 3

Tags

NGSS.MS-PS2-1

NGSS.MS-PS2-2

The illustration shows all the forces in Newtons (N) acting on a box. The sum of all the forces acting on the box results in a force acting on the box–

• to the right with a strength of 11 Newtons

• to the left with a strength of 7 Newtons

• to the right with a strength of 25 Newtons

• to the left with a strength of 6 Newtons

Tags

NGSS.MS-PS2-2

 Students are investigating how mass affects the force needed to move an object. They attached a wooden block to a spring scale and placed a 10 g mass on top of the block and pulled it 50 cm across the table. Which of the following changes to their setup would result in a larger force reading on the spring scale?

• Sliding the block 60 cm

• Attaching a larger spring scale

• Using a 20 g mass

• Using a circular piece of wood

Tags

NGSS.MS-PS2-1

NGSS.MS-PS2-2

Students are using an air rocket to investigate the relationship between force and an object’s motion. Students pump air into the rocket, and the compressed air pushes the rocket upward. In order to vary the amount of force acting on the rocket, which of the following should the students change in each trial?

• The length of the hose attached to the pump

• The distance traveled by the rocket

• The amount of air pumped into the rocket

• The height of the rocket from fins to cone

Tags

NGSS.MS-PS2-1

NGSS.MS-PS2-2

Which of the following graphs shows how the mass of an object affects the amount of force needed to move it?

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Tags

NGSS.MS-PS2-2