Science 9 Unit 8 Forces and Newtons Laws of Motion

When a pair of balanced forces acts on an object, the net force that results is

• greater in size than both forces combined.

• greater in size than one of the forces.

• equal in size to one of the forces.

• equal to zero.

  
  

As you push a cereal box across a tabletop, the sliding friction on the cereal box

• equals the weight of the box.

• acts in the direction of motion.

• is usually greater than static friction.

• acts in the direction opposite of motion.

What kind of friction occurs as a jet flies through the sky?

• fluid

• . static

• rolling

• sliding

  
  

The property of matter that resists changes in motion is called

• gravity.

• inertia.

• weight.

• friction.

Your weight equals your

• mass.

• mass multiplied by your speed.

• mass divided by the net force acting on you.

• mass multiplied by acceleration due to gravity.

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. An orange might roll off your cafeteria tray when you stop suddenly because of

• the orange’s inertia.

• the friction forces acting on the orange.

• the balanced forces acting on the orange.

• the centripetal forces acting on the orange.

  
  

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An object always accelerates in the same direction as which of the following?

• gravity

• net force

• air resistance

• static friction

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In which of the following are action and reaction forces involved?

• When a tennis racket strikes a tennis ball.

• When stepping from a curb.

• When rowing a boat.

• All of the above.

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The forces acting on a falling leaf are

• gravity and static friction.

• gravity and air resistance.

• weight and rolling friction.

• air resistance and fluid friction.

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An open parachute increases air resistance of a falling skydiver by

• reducing fluid friction.

• increasing surface area

• increasing the terminal velocity.

• decreasing the weight of the diver