8th Grade Forces, Motion, Gravity Mid-Unit Test

Four forces are acting on a box, as shown below.This box will increase in speed

• downward and to the left.
• downward and to the right.
• upward and to the left.
• upward and to the right.

What is one way you could reduce the friction between two surfaces?

• put salt on the surfaces
• put sand on the surfaces
• put carpet on the surfaces
• put oil on the surfaces

Kara pushes her big brother on a swing at the playground. After he gets off the swing, her little brother gets on. Kara finds that it is easier to push her little brother than it was to push her big brother.What is the MOST LIKELY reason for this?

• A smaller mass always moves faster than a larger mass.
• A smaller mass always moves slower than a larger mass.
• Less force is needed to move a larger mass the same distance.
• More force is needed to move a larger mass the same distance.

Objects tend to keep on doing what they are doing. This natural tendency to resist change in motion is called ___________

• inertia
• acceleration
• friction
• momentum

What type of force causes an ice skater to begin to move?

• balanced
• gravitational
• magnetic
• unbalanced

The diagram below shows a person pulling on a crate. The arrows show the forces acting on the crate. The numbers indicate the sizes of the forces.What is the net force (sum of the forces) acting on the crate?

• 15 N to the left
• 447 N up
• 475 N to the right
• 894 N down

Which of these is one of Newton’s laws of motion?

• An object’s momentum is the product of its mass and velocity.
• A moving object will continue moving until a force acts upon it.
• The force of gravity is proportional to the inverse square of the distance.
• The rate at which an object falls depends on the height from which it is dropped.

Which equation expresses Newton’s second law of motion?

• F = ma
• F = m/a
• F = m - a
• F = m + a

If all of the objects in the data table below have the same acceleration, which object will require the greatest force?

• 1
• 2
• 3
• 4

Which of the following indicate that an object has been subjected to an unbalanced force?

• The object speeds up.
• The object slows down.
• The object changes direction.
• Any of the above.