Accelerations are produced by
forces
How does acceleration of an object change in relation to its mass?
It is inversely proportional.
The acceleration produced by a net force on an object is:
inversely proportional to the mass of the object
directly proportional to the magnitude of the net force
in the same direction as the net force
When a woman stands with two feet on a scale, the scale reads 280 N. When she lifts one foot, the scale reads
280 N
Suppose the force of friction on sliding object is 25 N. The force needed to maintain a constant velocity is
25 N
A book weighs 4 N. When held at rest in your hands, the net force on the book is
0 N
An object has a constant mass. A constant force (with no opposing force) on the object produces constant
acceleration
A force of 3 N accelerates a mass of 3 kg at the rate of 1 m/s2. The acceleration of mass of 6 kg acted upon by a force of 6 N is
the same
A rock is thrown vertically into the air. At the very top of its trajectory the net force on it
is its weight (mg).
10. Pressure is defined as
force per area
Which of the following would exert the most pressure on the ground?
A woman standing in high heels
If you pull horizontally on a desk with force of 150 N and the desk doesn't move, the friction force must be 150 N. Now if you pull with 250 N so the desk slides at constant velocity, the friction force is
250 N
Consider a ball rolling down the decreasing slope inside a semicircular bowl (the slope is steep at the top rim, gets less steep toward the bottom, and is zero (no slope) at the bottom.) As the ball rolls from the rim downward toward the bottom, its rate
decreases
You are pulling on a block (with no angle) and you measure a frictional force of 50 N. Your object weighs 2 kg. Using 10m/s2 as your acceleration of gravity, what is the frictional coefficient ??
.4
A piece of sandpaper with a ? of .3 is attached to a block which has a weight of 50 N. What is its force of friction if it is pulled at a constant velocity.
15 N
Objects move only when a force is exerted
False
The acceleration of an object is inversely proportional to the net force acting on it
False
Air resistance is caused by friction between the air and an object moving through the air.
True
Pressure is defined as the force one object exerts on another object.
False
The speed of an object dropped in air will continue to increase without limit until it strikes the ground.
False
The acceleration produced by a net force on an object is:
directly proportional to the magnitude of the net force, in the same direction as the net force, and inversely proportional to the mass of the object.
If the force acting on a cart doubles, what happens to the cart's acceleration?
It halves
A girl whose weight is 200N hangs from a bar supported by two strands of rope. What is the tension in each strand?
100N
Pressure is defined as:
force per unit area
A tennis ball and a solid steel ball the same size are dropped at the same time. Which ball ahs greater force acting on it?
The steel ball
12. A tennis ball and a solid steel ball the same size are dropped at the same time. In the absence of air resistance, which ball has the greater acceleration?
Nonsense! They both have the same acceleration.
As he falls from a high-flying stationary helicopter, Bronco's velocity increases and his acceleration
Decreases
1You push with 30N on a 3-kg block and there are no opposing forces. What is the block's acceleration?
10m/s2
A 50-kg block of cement is pulled upward with a force of 600N. What is its acceleration?
12m/s2
Whenever one object exerts a force on a second object, the second object always exerts the same amount of force back on the first object
True
A rocket ship is pushed forward by gases that are forced out the back of the ship.
True
In order to make a cart move forward, a horse must pull harder on the cart than the cart pulls on the horse.
False
If a bicycle and a parked car have a head-on collision, the force of impact is greater on the bicycle
False
The earth and moon pull on each other with equal amounts of force
True
Whenever an object exerts a force on another object, the second object exerts a force of the same magnitude, but in the opposite direction to that of the first object
Always true
A high school student hits a nail with a hammer. During the collision, there is a force...
on the nail and also on the hammer
A woman weighing 500N sits on the floor. She exerts a force on the floor of
500N
As a 500N woman sits on the floor, the floor exerts a force on her of
500N
Forces always occur
in pairs
An unfortunate bug splatters against the windshield of a moving car. Compared to the force of the car on the bug, the amount of force of the bug on the car is
the same
An unfortunate bug splatters against the windshield of a moving car. Compared to the deceleration of the car, the deceleration of the bug is
larger
If a horse pulls on a wagon at rest, the wagon pulls back equally as much on the horse. Will the wagon be set into motion?
Yes, because there is a net force acting on the wagon.
A 60-kg person on in-line skates pushes against a wall with a force of 30N and recoils. What acceleration does that person experience?
.5 m/s2
A boxer punches a sheet of paper in midair, and brings it from rest up to a speed of 40m/s in 0.05s. If the mass of the paper is 0.01kg, what is the force of impact on the paper
8N
What is terminal speed? When a skydiver has reached terminal speed, what is the air resistance equal to? What is the skydiver's acceleration?
Terminal speed is the speed at which the force from the weight of the object equals the force of air resistance, so the acceleration is zero. When a skydiver reaches terminal speed, the air resistance is equal to the force of weight of the skydiver. At terminal speed, the sky diver's acceleration is zero.
Apply Newton's third law to a falling boulder, identifying the action and reaction forces. If a force is exerted on the earth, why doesn't it move? Explain.
Newton's third law states that whenever one object exerts a force on a second object, the second object always exerts the same amount of force back on the first object. In the situation of a boulder falling to earth, the action force is the boulder exerts a force on the earth. The reaction force is the earth exerts a force on the boulder. The forces of the falling rock and the earth are equal and opposite but they accelerate differently because of their masses. Newton's 2nd law says mass and acceleration are inversely proportional. Because the mass of the earth is so huge compared to the small mass of the boulder, we don't sense it infinitesimal acceleration.