Physics Final Unit 1: Laws of Motion & Mechanics

A hockey puck is set in motion across a frozen pond. If ice friction and air resistance are negligible, the force required to keep the puck sliding at constant velocity is

0 N

A 1-kg chunk of putty moving at 1 m/s collides with and sticks to a 5-kg bowling ball initially at rest. The bowling ball and putty then move with a momentum of __________ kg m/s

1

A 1-N apple falls off your head. While the apple is freely falling, the magnitude of the net force on it is

1 N

A rifle of mass 2 kg is suspended by strings. The rifle fires a bullet of mass 1/100 kg at a speed of 200 m/s. the recoil speed of the rifle will be

1 m/s

A 1- kg mass at Earth's surface weighs about

10 N

The force of friction on a sliding object is 10 N. The applied force needed to maintain a constant speed in the same direction is

10 N

An apple falls from a tree and falls 5 meters to hit Isaac Newton on the head (he is sleeping under the tree). It hits Isaac's head with a speed of about

10 m/s

A car accelerates at 2 m/s/s. Assuming the car starts from rest, how much time does it need to reach a speed of 30 m/s?

15 sec

A tow truck exerts a force of 3000 N on a car, accelerating it at 2 m/s 2. The mass of the car must be

1500 kg

Fido weighs 120 N and carries Trixie who weighs 40 N on her back. The support force on Fido's feet is

160 N

It takes 6 seconds for a chunk of zinc ore to fall to the bottom of the Dividend Mine down a mine shaft. How deep is it to the bottom of the shaft?

180 m

You're driving in a car at 50 km/h and bump into a car ahead traveling at 48 km/h in the same direction. The speed of impact is

2 km/h

A boat travels upstream against a current of 3 m/sec. If the speedometer of the boat indicates it is traveling 5 m/sec relative to the water, its speed relative to a person standing on the shore would be

2 m/sec

If a Jaguar sports car accelerates from zero to 100 km/h in 3.0 s its acceleration is

33.3 km/h/s

A free- falling object has a speed of 30 m/s at one instant. Exactly 2 seconds later its speed will be

50 m/sec

A person is attracted toward the center of Earth by a 500- N gravitational force. The force of attraction of Earth toward the person is

500 N

A Porsche can increase its speed from zero to 60 km/hr in 10 seconds. Its acceleration is

6 m/km/hr

A car accelerates from rest at 2 m/s/s. What is the speed 3 seconds after the car starts moving?

6 m/s

If a 60-kg parachutist is falling downward at a constant speed (and the weight of the parachute itself can be neglected), the friction force on the parachutist must be

600 N

The muzzle velocity of a gun is 100 m/s. Neglecting air resistance, at the end of 1 second, a bullet fired straight upwards toward the sky will have a speed of

90 m/s

A bug is smashed on the windshield of your car as you drive 60 mph down the freeway. The force was greater on the bug than on your car. T/F

F

Even when there is wind and air-resistance, a ball thown upward at a certain speed will return to its starting height with the same speed. T/F

F

Inertia is the force that resists any change in an object's state of rest or motion. T/F

F

The force that keeps the earth spinning on its axis is the force of inertia. T/F

F

The moon orbits the earth, therefore the force of gravity the earth exerts on the moon, must be greater than the force of gravity the moon exerts on the earth. T/F

F

You weight and mass remain constant as long as you are on the surface of the earth, regardless of where on the earth you are. T/F

F

A hockey puck hits and bounces off a glass safety window during a hockey game. Knowing about the change in velocity of the hockey puck at it bounces off the window, the time it takes to bounce, and the mass of the puck would enable us to determine the force that was exerted on the safty glass. T/F

T

A scientific hypothesis may turn out to be right or it may turn out to be wrong. If it is a valid hypothesis, there must be a test for proving it wrong. T/F

T

According to the law of falling bodies, the additional distance a falling object falls each succeeding second, follows the odd numbers. T/F

T

If a light-weight moving object collides with a more massive stationary object, the massive object will move faster after the collision if the light-weight object bounces back off the massive object. T/F

T

The actor, Brandon Lee, was killed by the firing of a gun loaded with blanks toward his chest at close range, during the making of the movie, The Crow. T/F

T

The direction of acceleration of a moving object is always the same as the direction of the net force acting on the object. T/F

T

The great advantage of SI (International System) units is that their subdivisions and multiples are in powers of 10. T/F

T

The law of falling bodies was further confirmed when an astronaut on the moon dropped a feather and a hammer from the same height and saw them hit the lunar surface simultaneously. T/F

T

Action and reaction forces comprise the parts of

a single interaction

A package falls off a truck that is moving at 30 m/s. Neglecting air resistance, the horizontal speed of the package just before it hits the ground is

about 30 m/s

A friend says that the heavyweight champion of the world cannot exert a force of 50 N on a piece of tissue paper with his best punch. The tissue paper is held in midair, no wall, no tricks. You

agree that it can't be done

Compared with a 1-kg block of solid iron, a 2-kg block of solid iron has twice as much

all of these

A scientific law or theory is valid

as long as it is not contradicted by new experimental findings

Lilies on a certain pond are found to double their number each day. If we were to make a graph of the number of lilies on the pond versus time, this graph would

be a curve that curves upward to the right

If an object moves with constant acceleration, the velocity of the object must

continually change by the same amount each second

An object is propelled along a straight-line path by a force. If the net force were doubled, its acceleration would

double

A freight train rolls along a track with considerable momentum. If it rolls at the same speed, but has twice as much mass, its momentum is

doubled

The force that accelerates a rocket in outer space is exerted on the rocket by the

exhaust gases

The scientific method is most effective in

explaining, organizing, and applying new knowledge

If you whirl a rock around you head at the end of a string, it will follow a circular path. If the string breaks, the tendency for the rock will be to

follow a straight-line path

Tension forces

have all of the above properties

Science is a body of knowledge that goes back to

humankind's beginnings

An object has twice as much mass as another object, then it also has twice as much

inertia

A glance at your speedometer will tell you your

instantaneous speed

A kilogram is a measure of an object's

mass

The average force that a bungee cord exerts on a jumper, multiplied by the time that the cord stretches, equals the jumper's change in

momentum

A ball is thrown vertically into the air. Because of air resistance, its time coming down compared to its time going up is

more

A car has a certain maximum acceleration. When it tows another twice- as- massive car its maximum acceleration is

one-third

Galileo's demonstration at the Leaning Tower of Pisa

refuted Aristotle's teachings.

After a ball tossed upward leaves your hand, the force of gravity on it

remains constant

A rifle recoils from firing a bulet. The speed of the rifle's recoil is small because the

rifle has more mass than the bullet

A sheet of paper can be withdrawn from under a glass of milk without toppling it if the paper is jerked quickly. This best demonstrates that

the glass of milk has inertia

Your weight is

the gravitational attraction between you and the earth

If in fact Galileo dropped a heavy ball and a light ball from the Leaning Tower of Pisa,

the heavy ball would have struck the ground first

A light woman and a heavy man jump from an airplane at the same time and open their same- size parachutes at the same time. Which person will get to a state of zero acceleration first?

the light woman

An object weighs 30 N on Earth. A second object weighs 30 N on the Moon. Which has the greater mass?

the one on the moon

A certain rock weighs 30 N on the moon. Meanwhile a particular brick weighs 30 N on the earth. Which one has the greater mass?

the rock on the moon

A force of 1 N accelerates a 1- kg mass at 1 m/s2. The acceleration of a 2- kg mass acted upon by a force of 2 N is

the same

The difference between impact force and impulse involves the

the time a force acts

In order to catch a ball, a baseball player extends the hand forward before impact with the ball and then lets it ride backward in the direction of the ball's motion upon impact. Doing this reduces the force of impact on the player's hand principally because the

time of impact is increased

If you toss a ball straight upward at 40 m/s with no air resistance, one second before it reaches the top of its path its speed is

zero