Ch. 5 Test
Two objects, one twice as massive as the other, are pulling on a rope toward each other on a frictionless surface and are 12 m apart. They meet face to face. What is the distance the more massive person moved?
4m
What is the resultant of a vertical vector of 3 units combined with a horizontal vector of 4 units?
5 units (solve using Pythagorean theorem: a² + b² = c²)
What is the magnitude of the vertical component of a 10 unit vector 60° clockwise from the vertical?
5 units (solve using cos60° × 10)
If one end of a rope is pulled with a force of 50N, while the other end is pulled with 50N, what is the tension of the rope?
50N
An airplane travels at 100 km/h toward the northeast (45° north of east). What is the velocity due north?
70.7 km/h (solve by doing cos45° × 100)
The resultant of a 30 N force and a 40 N force cannot possibly be what?
80 N
What is acceleration directly proportional to?
force
When a ball is bounced on a floor, the acceleration on the ball between bounces is eqaul to what?
g (the acceleration of gravity)
With negligible air resistance, once a tossed ball leaves your hand, what is the only force that acts on it?
gravity
When Nellie Newton hangs by a pair of ropes at different angles to the vertical, in which rope is the rope tension greater?
in the rope with the smallest angle to the vertical
When you jump vertically upward, strictly speaking, what do you cause the Earth to do?
move downward
What must there be to produce acceleration to a system?
net force
Are the accelerations of a pair of action-reaction forces always equal?
no
Does the force due to gravity that acts on a block of ice that slides down an icy ramp change as the angle of the ramp changes?
no, it does not change
When a ball is tossed upward at an angle (disregarding air resistance), does the horizontal component of the initial velocity vector change?
no, the horizontal component remains the same
Whenever one object exerts a force on a second object, the second object exerts a force on the first that is what?
opposite in direction, equal in magnitude, and occurs at the same time
How must a pair of action-reaction forces always occur?
simaltaneously
An aardvark and a Land Rover traveling at the same speed have a head on collision. Which one undergoes the greatest change in velocity?
the aardvark
As a dropped ball falls toward the surface of the Earth there is an action reaction force pulling the ball to the ground. What is the reaction force?
the ball pulls the Earth upward
A boulder falls due to gravity. What is the reaction to the force on the boulder?
the boulder pulling up on the earth
When a cannonball is fired from a cannon, what undergoes the greatest acceleration?
the cannon ball
A shoe on an inclined surface barely remains at rest when friction equals what?
the component of mg parallel to the surface
When the neck of an air-filled balloon is untied and air escapes, the balloon shoots through the air. The force that proves the balloon is provided by what?
the ejected air
Where does the force the casues a ball to bounce off the floor come from?
the floor
If action is a foot kicking a soccer ball, the reaction is an equal force on what?
the foot
When an ape is suspended at rest by holding rope with one hand and the side of the cage with the other, all of the force vectors add up to what?
the force vectors add up to 0
As the sloped surface supporting a shoe become steeper, what happens to the friction needed to keep the shoe at rest?
the friction increase
In a tug-of-war, what does the winning team exert the most force on?
the ground
When a horse walks and he pushes on the ground to the left, how does the ground push?
the ground pushes the horse to the left
The force that propels a heavy truck along a highway is provided by what?
the highway pushing back on the wheels of the truck
The amount of force with which a boxer's punch lands depends on what?
the mass of what's being hit
As the sloped surface supporting a shoe become steeper, what happens to the normal force?
the normal force becomes less
After a head-on collision between two different mass objects traveling at the same speed, which object undergoes the greatest change in velocity?
the object with the lower mass
You cannot exert a force on a floor or any other surface unless what happens?
the other surface simultaneously exerts the same amount of force on you
When the force exerted on the tires of a car directly accelerates it along a road, what is the force exerted by?
the road
Each pulls on the moon with a certain force relative to this force, the full of the moon on earth is what?
the same
The impact force between to objects is what for both objects?
the same
If there is one force present, what else is always present?
a corresponding reaction force
You can run horizontally at 4 m/s in a vertically falling rain that falls at 4 m/s. Relative to you, the raindrops are facing at an angle of what?
45°
If acceleration is 0, what must the sum of all forces equal?
0
What are the three steps to solve vector problems?
1.) make a vector sketch and label all given and known information 2.) identify know and unknown (what you want to find) 3.) use the provided equations to find the unknown
When you push against a wall, nothing can happen unless what two things happen?
1.) there is an interaction between you and the wall and 2.) the wall pushes back on you
When a ball falls downward, what are the three things its net force may be equal to?
1.) zero 2.) equal to its weight 3.) equal to its weight minus air drag
What does double the mass eqaul
1/2 the acceleration
What does an interaction require?
2 objects
An astronaut with a mass of 80kg weighs 800N on Earth. What is his weight on Mars where the acceleration of gravity is 3.7 m/s²?
296N (W=Fg: 80kg(3.7 m/s²) = 296N)
What is the tension in a rope that is pulled by two people, each exerting 300N of force?
300N
The air speed of an airplane is 300 km/h. It is caught in a 100 km/h crosswind (90° to its path in the air). What is the across the ground below?
316 km/h (solve using Pythagorean theorem: a² + b² = c²)
An axe is swung against a tree with a blow of 4000 N. What is the force that acts on the axe during this event?
4000 N
Can a boxer exert a 60N force on a piece of paper?
No
When a squid pushed against water, why does the squid move forward?
becasue the water exerts a net forward force
Two identical carts have a compressed spring between them. When the spring is released, the carts recoil from each other with oppositely directed accelerations that are what?
equal
For every action force, there must be a reaction force that is what?
equal in magnitude and opposite in direction
Horizontal and vertical components of velocity are equal when the projection angle is what?
equal to 45°
A vertically falling snow makes slanted 45 degree streaks on the side of the window of a moving car. What is the speed of the car?
equal to the speed the snowflake
What is acceleration inversly proportional to?
mass
What happens to the normal force that acts on a block of ice that slides on a ramp?
it gets progressively less as the slope of the ramp increases
When an aardvark and a Land Rover travelling at the same speed collide head on, what is the impact force?
it is the same for both of them
A pair of carts with a compressed spring between them is set in motion. If onr cart moves at twice the speed of the other, what is its mass?
its mass is 1/2 the mass of the other cart
When a person stands on a horizontal surface, the person's weight and the noraml force have the same what?
magnitude
A mosquito has a collision with the windshield of a massive high-speed truck. The force of impact on the mosquito is ___________ the force on the truck, and the acceleration of the mosquito is ___________ the deceleration of the truck.
the same as; more than
A force is a push or pull that is required to the change of what?
the state of motion of an object
When a person hangs suspeneded from a pair of ropes that are not vertical, what is the tension in each rope?
the tension in each rope is more than half her weight
A massive truck and a golf cart have a head-on collision with equal amounts of force. The least amount of acceleration occurs for which object?
the truck
As the sloped surface supporting a shoe become steeper, what happens to the shoe's weight?
the weight remains the same
A force interaction requires at least what?
two forces
When does a shoe on an inclined surface barely remain at rest?
when friction equals the parallel force of the weight
When can the net force of a kicked soccer ball be zero?
when it is kicked by two feet with equal and opposite amounts of force
Are the forces of a pair of action-reaction forces always equal?
yes
Does the normal force that acts on a block of ice that slides on a ramp change as the the slope of the ramp increases?
yes, it decreases
When a ball is tossed upward at an angle (disregarding air resistance), does the vertical component of the initial velocity vector change?
yes, the vertical component increases up to the top of the flight, then decreases at the same rate to the ground
What can you not do when your hands are in contact with each other?
you can not push harder on one hand than the other