Chapter2 Flashcards
(23 cards)
Consider a cart pushed along a track with a certain force. If the force remains the same while the mass of the cart decreases to half, the acceleration of the cart
- remains the same
- halves
- doubles
- changes unpredictably
Doubles
Push a cart along a track so twice as much net force acts on it. If the acceleration remains the same, what is a reasonable explanation?
- the mass of the cart doubled when the force doubled
- the track is not level
- the cart experiences friction that it didn’t before
- the twice and much net force is in error
The mass of the cart doubled when the force doubled
What a 10-kg block is simultaneously pulled westward with 25N and eastward with 15N, it undergoes an acceleration of
- 2 m/s/s to the East
- 2 m/s/s to the West
- 4 m/s/s to the East
- None of the above
None of the above
What a 25N falling object encounters 15 N of air resistance, the net force on it is
- 10N and it accelerates downward at less than g
- 10N and it accelerates downward at g
- 10N and it accelerates downward at more than g
- 25N and it no longer accelerates
10N and it accelerates downward at LESS THAN g
A falling object that has reached its terminal velocity continues to
- gain speed
- gain acceleration
- both
- neither
Neither
As a falling object gains speed in falling, air drag on it
- decreases
- remains essentially constant
- increases
- none of the above
Increases
Toss a rock straight up in the air, and at the top of its path its acceleration is
- zero
- g
- less than g, and more than zero
- none of these
g
Your friend says that the heavyweight champion of the world cannot exert a force of 50N on a piece of paper with his best punch. The tissue paper is held in midair, no wall, no tricks.
- you agree it can’t be done
- you have reservations about this claim
- you disagree, for a good punch easily delivers this much force
- you think he is crazy
You agree it can’t be done
What a bat hits a ball, the ball simultaneously
- may exert the same amount of force on the bat
- exerts the same amount of force on the bat
- exerts less force on the bat
- exerts more force on the bat
Exerts the same amount of force on the bat
The force exerted on the tires of a car to directly accelerate it along the road is exerted by the
- grooves in the tire surface
- friction on the tires themselves
- interaction between the front and rear tires
- pavement
Pavement
The team to win in a tug of war is the team that
- pulls harder on the rope to produce greater tension
- pushed harder on the ground
- both of these
- neither of these
Pushes harder on the ground
A massive fast-moving car collides head on with a light slow-moving car. The force of impact is greater on the
- small car
- heavy car
- actually, the force is the same on each
- more information is needed to answer this correctly
The force is the same on each
A massive fast-moving car collides head on with a light slow-moving car. The acceleration is greater on the
- small car
- heavy car
- same for both
- more information is needed
Small car
An airplane’s speed across the ground can be affected by the wind. When an airplane encounters a crosswind at 90 degrees to the plane, the speed of the plane across the ground below is
- decreased
- increased
- unaffected
Increased
Suppose that Nellie Newton hangs from two strands of rope that form equal angles to the vertical. Then the tension in each rope
- is more than her weight
- is less than her weight
- may be more, or may be less than her weight
May be more or may be less than her weight
Newton’s First Law of Motion
Every object continues in a state of rest, or in a state of motion in a straight line at constant speed, unless acted upon by a net force - INERTIA
Newton’s Second Law of Motion
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 Third Law of Motion
Whenever one object exerts a force on a second object, the second object exerts an equal and opposite force on the first object
Inertia
The property of all matter to RESIST changes in motion
Acceleration =
Force/mass
If the net force acting on an object is double, what happens to it’s acceleration?
It is doubled
If the mass of an object is doubled, what happens to it’s acceleration?
It is halved
True or false: The greater the mass of an object, the stronger is the gravitational pull between it and Earth.
True
