Unit 4 Forces & Motion

An antelope is being chased across the savannah by a hungry lion. The lion runs at a constant speed. How might the antelope use its velocity to escape the lion? Choose the three statements that apply.

• It can run at the same speed but change direction.

• It can run in the same direction but increase its speed.

• It can both increase speed and change direction.

• It can decrease speed but continue running in the same direction.

The bumpy pattern on the soles of shoes is called the tread. Melanie and Keisha are at the store looking at the treads on different basketball shoes. They want new shoes so that they do not slide around on the basketball court. Which of these situations produces the most friction between the shoes and the floor?

• a girl with less mass wearing shoes with more tread

• a girl with less mass wearing shoes with less tread

• a girl with greater mass wearing shoes with more tread

• a girl with greater mass wearing shoes with less tread

Anna hits a golf ball, and it soars through the air toward the green. It travels in an arc over the ground. Which statement does not describe the ball’s acceleration before it stops?

• It increases speed.

• It decreases speed.

• It changes its overall direction.

• It moves in the same direction.

Carmen is helping load furniture and boxes onto a moving truck. She picks up boxes of her things, places them on a cart, and pushes the cart to the moving van. What type of force Carmen is using?

Andrew plays trumpet in the concert band. He holds the trumpet still at his side until it is time for him to play. When it is time, he brings the trumpet up to his mouth and starts to play. Which statement correctly connects the motion of the trumpet with Newton’s first law of motion?

• A tuba has more mass than a trumpet, so it has greater inertia

• The trumpet automatically stops moving without a force acting on it.

• The trumpet starts moving because a net force overcomes the trumpet's inertia.

• Andrew exerts an action force on the trumpet, and the trumpet exerts a reaction force on Andrew.

Suppose a bulldozer is being hauled on the back of a flatbed truck at 50 km/h to a construction site. From which reference point would the bulldozer not appear to be moving?

• the road

• a traffic light

• the truck driver

• a roadside tree

Jerome has a tow truck, and he is in charge of moving several vehicles for the city. He wants to explain to his niece how towing vehicles relates to Newton’s second law. Which statement should he use?

• The greater the vehicular mass, the less force the tow truck will use.

• The greater the vehicular mass, the more force the tow truck will use.

• The vehicular mass has no effect on the amount of force the tow truck uses.

• The vehicular mass pulls on the tow truck in the opposite direction.

Ahmed saw all of these things as he walked to school this morning. Which one is an example of a force pushing downward toward the ground?

• A bird sat on a telephone wire.

• A woman moved her child from one place to another in a wagon.

• A man pulled weeds in his garden.

• A dog tugged on a rope held by a child.

Miko is blowing up balloons for her little sister’s birthday party. One of the balloons slips out of her hand before she ties it off, and it shoots through the air until it is empty. Which statement explains what caused the balloon to accelerate?

• The air leaving through the balloon's mouth pushes on the air surrounding the balloon, so the balloon experiences a net force.

• All air surrounding the balloon pushes the balloon forward.

• The mass of the air leaving the balloon is greater than the mass of the balloon, so the balloon moves forward.

• When the balloon pushes on the leaving air, the leaving air pushes back on the balloon, so the balloon experiences a net force.

Mr. Wang works in a recycling center. Recyclable materials arrive at the center mixed together. Workers use magnets to separate steel cans from other items. Which two statements are true about the force between a steel can and a magnet?

• Gravity pushes the can toward the magnet.

• The force between the can and the magnet is a noncontact force.

• The attraction between the can and the magnet is a pull.

• The attraction between the can and the magnet is a push.