4th grade Force and Motion: Friction

After reading the text, which surface would a skateboard experience the least amount of friction?

• Thick grass

• Bumpy cement road

• Smooth cement sidewalk

• Sandy parking lot

Which statement best describes the frictional forces between a skateboard and a surface?

• Rough surfaces produce more friction.

• Two surfaces must touch to create friction.

• Friction causes an object’s motion to slow or stop.

• Smooth surfaces produce less friction.

Friction is a force that affects _____________. Increasing friction requires _____________ force to move objects. Decreasing friction requires _____________ force to move objects.

• energy

• motion

• less

• more

• speed

After watching the video about friction, which statement is true?

• A drag plate increases motion by decreasing friction.

• A drag plate increases friction to decrease motion.

• A drag plate decreases speed by decreasing friction.

• A drag plate decreases motion by increasing speed.

Which statement best supports the definition of Friction?

• Pushing down on the drag plate decreases the friction between the plate and the ground.

• Friction is increased between the sled and the ground when mass is added to the drag plate.

• Increasing the amount of force on the drag plate increases the amount of friction between the plate and the ground.

• Pushing the drag plate increases the speed of the sled.

How does friction work?

• Friction is a force that opposes motion between two surfaces in contact.

• Friction is a type of energy that accelerates objects.

• Friction is a magnetic force that attracts metals.

• Friction is a chemical reaction between surfaces.

Describe how materials can increase friction.

• By making surfaces smoother

• By increasing surface roughness

• By reducing contact area

• By using lubricants

Describe how materials can decrease friction.

• By increasing surface roughness

• By using lubricants

• By increasing the contact area

• By applying more force