Forces in MotionForces in Motion

Galileo proved that the rate at which Galileo proved that the rate at which an object fallsan object falls

is not affected by the mass.is not affected by the mass.

If three balls of different materials If three balls of different materials were dropped at the same time from were dropped at the same time from the same height, which would hit the the same height, which would hit the ground first? (Assume there is no air ground first? (Assume there is no air

resistance.)resistance.)

They would hit at the same time.They would hit at the same time.

Air resistance isAir resistance is

fluid friction.fluid friction.

The amount of air resistance acting on The amount of air resistance acting on an object depends on the object’san object depends on the object’s

size and shape.size and shape.

____ is reached when a falling object ____ is reached when a falling object stops accelerating. The object is falling stops accelerating. The object is falling

at a constant speed.at a constant speed.

Terminal velocityTerminal velocity

Parachutes slow skydivers to a safer Parachutes slow skydivers to a safer terminal velocity because parachutesterminal velocity because parachutes

increase air resistance.increase air resistance.

An object is in ____ only if gravity is An object is in ____ only if gravity is pulling it down and no other forces are pulling it down and no other forces are

acting on it.acting on it.

free fallfree fall

____ is a measure of gravitational ____ is a measure of gravitational force.force.

WeightWeight

Astronauts float inside the space Astronauts float inside the space shuttle because theyshuttle because they

are in free fall.are in free fall.

Orbital motion is a combination of Orbital motion is a combination of forward motion andforward motion and

free fall.free fall.

The unbalanced force that causes The unbalanced force that causes objects to move in a circular path is objects to move in a circular path is

calledcalled

centripetal force.centripetal force.

____ is the curved path an object ____ is the curved path an object follows when thrown or propelled near follows when thrown or propelled near

the surface of Earth.the surface of Earth.

Projectile motionProjectile motion

The curved path traveled by a thrown The curved path traveled by a thrown baseball is known asbaseball is known as

projectile motion.projectile motion.

Because of projectile motion, when Because of projectile motion, when aiming at a target you should always aiming at a target you should always

aimaim

above the bull’s eye.above the bull’s eye.

Catapults createCatapults create

projectile motion.projectile motion.

According to Newton’s first law of According to Newton’s first law of motion, a moving object that is not motion, a moving object that is not

acted on by an unbalanced force willacted on by an unbalanced force will

remain in motion.remain in motion.

____ is the tendency of all objects to ____ is the tendency of all objects to resist any change in motion.resist any change in motion.

InertiaInertia

____ is the amount of matter in an ____ is the amount of matter in an object, and its value does not change.object, and its value does not change.

MassMass

If a car driver suddenly makes a sharp If a car driver suddenly makes a sharp turn, the passenger slides to the side turn, the passenger slides to the side

of the car because ofof the car because of

inertia.inertia.

According to Newton’s second law of According to Newton’s second law of motion to increase acceleration you motion to increase acceleration you

mustmust

increase force or decrease mass.increase force or decrease mass.

Newton’s third law of motion states Newton’s third law of motion states that whenever one object exerts a that whenever one object exerts a

force on a second object,force on a second object,

the second object exerts an equal and the second object exerts an equal and opposite force on the first object.opposite force on the first object.

____ is a property of a moving object ____ is a property of a moving object that depends on the object’s mass and that depends on the object’s mass and

velocity.velocity.

MomentumMomentum

A golf ball and a bowling ball are A golf ball and a bowling ball are moving at the same velocity. Which moving at the same velocity. Which

has more momentum?has more momentum?

The bowling ball, because it has more The bowling ball, because it has more mass.mass.

When you bump into someone When you bump into someone standing still, you can knock them over standing still, you can knock them over

because ofbecause of

momentum.momentum.