The Physical World: Chapter 1-2
Two people each pull with 300 N on a rope in a tug of war. What is the net force on the rope?
0N
If you pull horizontally on a crate with a force of 200 N, it slides across the floor in dynamic equilibrium. How much friction is acting on the crate?
200N
A 300-kg bear grasping a vertical tree slides down at constant velocity. The friction force between the tree and the bear is
3000N
The sketch shows a painter's scaffold in mechanical equilibrium. The person in the middle weighs 500 N, and the tensions in each rope are 400 N. What is the weight of the scaffold?
300N
Two people each pull with 300 N on a rope in a tug of war. How much force is exerted on each person by the rope?
300N
A different scaffold that weighs 400 N supports two painters, one 500 N and the other 400 N. The reading in the left scale is 800 N. What is the reading in the right-hand scale?
500N
In science, and educated guess is a
Hypothesis
A force of gravity pulls downward on a book on a table. What force prevents the book from accelerating downward?
Support
A sheet of paper can be withdrawn from under a container of milk without toppling it if the paper is jerked quickly.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: 1.gravity tends to hold the milk carton secure 2. the milk carton has inertia. 3. the milk carton has no acceleration. 4. there is an action-reaction pair of forces. 5. none of these
The milk carton has inertia
Which of the following is a scientific statement? There are parts of the universe that will never be found by man. Matter is filled with undetectable particles. there are things we will never know about. The moon is made of green cheese.
The moon is made of green cheese.
The synthesis of a large collection of information that contains well-tested and verified hypotheses about certain aspects of the world is known as a scientific
Theory
When a rocket ship accelerating in outer space runs out of fuel, it: 1.accelerates for a short time, then 2.slows down to a constant velocity. 3. no longer accelerates. 4.accelerates for a short time, slows down, and eventually stops.
accelerates for a short time, slows down, and eventually stops.
According to Newton's law of inertia, a railroad train in motion should continue going forever even if its engine is turned off. We never observe this because railroad trains 1.Move too slowly 2. are much too heavy 3. always have forces that oppose their motion 4. Must go up and down hills
always have forces that oppose their motion
The statement, "There are regions beneath the Earth's crust that will always be beyond the reach of scientific investigation," is a
speculation
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
