Year 3 Science Forces: check-up and practice test questions

Method. Look at the right-hand picture.

1. Read the picture. The rope and the arrow are on the right, pointing to the hand that pulls.
   towards the hand
2. Write the answer.
   towards

Check. A pull moves the box towards the person. ✓

Method. Read the key idea in section 9.5.

1. Read the definition. Friction is a force that slows down a moving object when two surfaces rub.
   friction
2. Write the answer.
   friction

Check. Friction acts between the box and the table. ✓

Method. Read the effects in section 9.2.

1. Read the effect. A force can start a still object moving.
   moving
2. Write the answer.
   moving

Check. A kick starts a still ball moving. ✓

Method. Read the key idea in section 9.3.

1. Read the key idea. Magnetic forces can act at a distance, so a magnet can pull a steel paper clip across a small gap.
   yes
2. Write the answer.
   yes

Check. Magnetic forces can act without touching. ✓

Method. Find the shortest bar.

1. Look at the bars. The shortest bar is the sandpaper, at 30 cm.
   shortest bar
2. Read the label. The label under that bar says Sandpaper.
   Sandpaper
3. Write the answer.
   Sandpaper

Check. The bar for the sandpaper is much shorter than the tray. ✓

Method. Think about the examples in section 9.5.

1. Read the examples. Shoes grip the floor, brakes slow a bicycle, and tyres grip the road.
   helps
2. Write two. Any two of these examples is correct.
   two examples
3. Write the answer.
   Accept any two of: stopping us from slipping, gripping the road, stopping a bicycle, gripping a jar lid.

Check. Friction helps when things grip. ✓

Method. Read the definition in section 9.6.

1. Read the definition. Water resistance is a force that acts on moving things in water, and slows them down.
   water resistance
2. Write the answer.
   water resistance

Check. Air resistance is the same kind of force, but in air. ✓

Method. Think about the direction of the force.

1. Think about the sledge. The sledge moves towards Ruby, so she pulls it.
   towards Ruby
2. Name the force. A force that moves something towards you is a pull.
   pull
3. Write the answer.
   pull

Check. A push moves something away from you. ✓

Method. Think about each force.

1. Think about the hand. The hand must touch the box to push it.
   touch
2. Think about the magnet. The magnet can pull the clip across a gap, so it does not need contact.
   does not need contact
3. Write the answer.
   a hand pushing a box

Check. Magnetic forces can act at a distance. ✓

Method. Think about the air each one catches.

1. Think about the flat sheet. The flat sheet is wide, so it catches more air.
   catches more air
2. Write the sentence. More air resistance slows it down more.
   more air resistance
3. Write the answer.
   Accept any sentence that says the flat sheet catches more air, so it has more air resistance.

Check. Both shapes are made of the same paper. ✓

Method. Think about the word for both a push and a pull.

1. Read the definition. A force is a push or a pull.
   force
2. Write the answer.
   force

Check. A push and a pull are both forces. ✓

Method. Think about the direction the sledge moves.

1. Read the sentence. The sledge moves towards Ruby.
   towards Ruby
2. Name the force. A force that moves something towards the person is a pull.
   pull
3. Write the answer.
   pull

Check. A push would move the sledge away from Ruby. ✓

Method. Read the labels in the picture.

1. Find the start picture. The label of the picture where a push starts the ball moving is Start.
   Start
2. Find the direction picture. The label of the picture where a kick sends the ball a new way is Change direction.
   Change direction
3. Write the answer.
   Start and Change direction

Check. The other pictures show stop, speed up and slow down. ✓

Method. Think about which force can act at a distance.

1. Think about each action. The hand and the rope must touch what they move. The magnet can pull across a gap.
   magnet
2. Write the action. So the action that does not need contact is the magnet pulling the paper clip.
   magnet and paper clip
3. Write the answer.
   A magnet pulls a steel paper clip across a small gap

Check. Magnetic forces can act at a distance. ✓

Method. Add the three trials, then divide by three.

1. Add them. The three trials add together to make 240 cm.
   82 + 78 + 80 = 240
2. Divide by three. Divide 240 by 3 to get the average.
   240 divided by 3 is 80
3. Write the answer.
   80

Check. Check: 80 + 80 + 80 = 240. ✓

Watch out. Divide by the number of trials, which is three.

Method. Think about the examples of friction.

1. Think about helping. Shoes gripping the floor help us walk without slipping.
   helps
2. Think about getting in the way. A sledge slowing down on the grass gets in the way.
   gets in the way
3. Write the answer.
   Accept any one helping example, such as shoes gripping the floor, and any one slowing example, such as a sledge slowing on the grass.

Check. Friction helps when things grip, and gets in the way when it slows things down. ✓

Method. Think about the air each shape catches.

1. Think about the shapes. The flat sheet is wide, so it catches more air and falls more slowly.
   flat sheet
2. Name the force. The force from the air that pushes against a falling object is air resistance.
   air resistance
3. Write the answer.
   flat sheet, air resistance

Check. The crumpled ball catches less air. ✓

Method. Think about the air.

1. Think about the surface. A bigger flat surface catches more air as it moves.
   more air
2. Explain the reason. So it has more air resistance, which slows it down more.
   more air resistance
3. Write the answer.
   yes. Accept any sentence that says a bigger flat surface catches more air, so it has more air resistance.

Check. The flat sheet falls more slowly than the crumpled ball. ✓

Method. Think about the force in water.

1. Name the force. The force from water that slows down a moving object is water resistance.
   water resistance
2. Say the direction. It pushes back against the motion of the plate.
   against the motion
3. Write the answer.
   water resistance; against the motion

Check. Water resistance pushes back against the motion. ✓

Method. Think about each force.

1. Read the first force. Mo pushes a still ball, so the push starts it moving.
   started it moving
2. Read the second force. Priya stops it with her hand, so the hand stops it.
   stopped it
3. Write the answer.
   Accept any answer that says the first push started the ball moving, and the hand stopped it.

Check. Forces can start and stop moving objects. ✓