Chapter 2
Ten seconds after starting from rest, afreely falling object will have aspeed of about
100m/s
An apple falls from a tree and hits the ground 5m below. It his the ground with a speed of about
10m/s
A ball is thrown 125m upward and then falls the same distance back to the earth. Neglecting air resistance, its total time in the air is about
10s
A tow truck exerts a force of 3000N on a car, accelerating it at 2m/s/s. What is the mass of the car?
1500kg
A car has a mass of 1000kg and accelerates at 2m/s/s. What is the magnitude of the force exerted on the car?
2000N
If a freely falling object were somehow equipped with a speedometoer on a planet where the acceleration due to gravity is 20m/s/s, then its speed reading would increase each second by
20m/s
If a rocket accelerates from rest at a rate of 50m/s/s for 10s, the distance it will cover during this time is about
2500m
A girl pulls on a 10kg wagon with a constant force of 30N. Whaat is the wagon's acceleration in meters per second per second?
3.0
A 500N parachutist opens his chute and experiences an air resistance force of 800N. The net force on th parachutist is
300N upward
If a baseball being thrown goes from zero to 30m/s in 0.1s, what is its average acceleration?
300m/s/s
The muzzle velocity of a certain gun is 100m/s. Neglecting air resistance, at the end of 1s a bullet fired straight up into the air will have traveled a distance of about
(100-5)m
A sack of potates weighing 200N falls from an airplane. As the velocity of fall increases, air resistance also increases. When air resistance equals 200N, the sack's acceleration in meters per second per second is
0
An object travels 8m in the first second of travel, 8m again during the second second of travel, and 8m again during the third second. Its acceleration in meters per second is
0
A skydiver of mass 100kg experiences air resistance of 500N, and an acceleration of about
0.5g
A 10N falling object encounters 10N of air resistance. The net force on the object is
0N
A hockey puck is set in motion across a frozen pond. If ice friction and air resistance are neglected, the force required to keep the puck sliding at constant velocity is
0N
A 10kg block is pushed across a horizontal surface with a horizontal force of 20N against a friction force of 10N. The acceleration of the block in meters per second per second is
1
Starting from rest, the sitance a freely falling object will falll in 0.5s is about
1.25m
The vertical height attained by a basketball player who achieves a hang time of a full 1s is about
1.2m
A rock is thrown vertically into the air. At the top of its path, its acceleration in meters per second per second is about
10
Two people, one twice as massive as the other, attempt a tug-of-war with 12m of rope on frictionless ice. After a brief time, they meet. The heavier person slides a distance of
4m
A person is attracted toward the center of the Earth by a 500N gravitational force. The force of attraction of the Earth toward the person is
500N
When a woman stands at rest with two feet on a scale, the scale reads 500N. When she gently lifts one foot, the scale reads
500N
Starting from rest, the distance a freely falling object will fall in 10s is about
500m
A 10N falling object encounters 4N of air resistance. The magnitude of the net force on the object is
6N
A car accelerates from rest a 2m/s/s. What is its speed 3s after the car starts moving?
6m/s
When acceleration is g
Free fall - when the only force action on a falling object is gravity, the object is in free fall. Free fall = 10m/s/s
Newton's 3rd Law of Motion
Law of Action and Reaction: Whenever one object exerts a force on a second object, the second object exerts an equal and opposite force on the first.
Arnold Strongman and Suzie Small have a tug-of-war on a polished floor. Arnold wears socks and Suzie wears gym shoes. The likely winner is
Suzie
Newton's 2nd Law of Motion
The Law of Acceleration: The acceleration produced by a net force on an object is directly proportional to the net force, is in the same direction as the net force, and is inversely proportional to the mass of the object.
Newton's 1st Law of Motion
The Law of Inertia: Every object continues in a state of rest or of uniform speed in a straight line unless acted on by a nonzero force.
A Mack truck and a Volkswagen traveling at the same speed have a head-on collision. The vehicle to undergo the greatest change in velocity will be the
Volkswagen
A player his a ball with a bat. The action force is the impact of the bat against the ball. The reaction to this force is the
force of the ball against the bat
A bullet is fired straight down from the top of a high cliff. Neglecting air resistance, the acceleration of the bullet in meters per second per second is
g
An object is propelled along a straight-line path in space by a force. If the mass of the object somehow becomes twice as much, its acceleration
halves
A force is a vector quantity because it has both
magnitude and direction
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
A sheet of paper can be withdrawn from under a container of milk without toppling it if the paper is jerked quickly. This best demonstrates that
the milk carton has inertia
The force required to maintain an object at a constant velocity in free space is equal to
zero
