Homework

Physics 101 - Homework 8

Instructions: Complete this form and click submit. The answers will be posted on the course home page after the due date and before the next exam. If you want to change any of your answers after you click submit, then go back and give your answers again and click submit.

Your Name: e.g. John Doe

Your Campus ID: e.g. 12345678

Your SFA Email Address: e.g. doejd@titan.sfasu.edu

Due Date 12/7/2007 5:00PM

0. Some of the questions below may have been modified from the in-class handout. Try to answer these first without looking at the handout, then study the handout, modify your answers if necessary and click Submit.
I understand
I do not understand

1. Inside a freely-falling elevator, there would be no
(a) gravitational force on you.
(b) apparent weight for you.
(c) both of these
(d) none of these

2. Which is most responsible for the ocean tides?
(a) ships
(b) continental drift
(c) the moon
(d) the sun

3. Padded dashboards in cars are safer in an accident than nonpadded ones because an occupant hitting the dash has
(a) increased time of impact.
(b) decreased impulse.
(c) decreased impact force.
(d) a and b above.
(e) a and c above.

4. Two identical gliders slide toward each other on an air track. One moves at 1 m/s and the other at 2 m/s. They collide and stick. The combined mass moves at
(a) 3/4 m/s.
(b) 1/3 m/s.
(c) 1/6 m/s.
(d) 1/2 m/s.
(e) 1.5 m/s.

5. A 5-kg fish swimming at a speed of 1 m/s swallows an absent-minded 1-kg fish at rest. The speed of the larger fish after lunch is
(a) 1/2 m/s.
(b) 2/5 m/s.
(c) 5/6 m/s.
(d) 6/5 m/s.
(e) 1 m/s.

6. A moving object on which no forces are acting will continue to move with constant
(a) impulse.
(b) momentum.
(c) acceleration.
(d) all of these
(e) none of these.

7. When you are in the way of a fast-moving object and can't get out of its way, you will suffer a smaller force of impact if you decrease its momentum over a
(a) short time.
(b) long time.
(c) same way either way.

8. When you jump from an elevated position you usually bend your knees upon reaching the ground. By doing this, you make the time of the impact about 10 times as great as for a stiff-legged landing. In this way the average force your body experiences is
(a) less than 1/10 as great.
(b) about 1/10 as great.
(c) about 10 times as great.
(d) more than 1/10 as great.

9. If you push an object with twice the work input for twice the time, your power input is
(a) four times as much.
(b) twice.
(c) the same amount as for half the work in half the time.

10. Whereas impulse involves the time that a force acts, work involves the
(a) time and distance that a force acts.
(b) distance that a force acts.
(c) acceleration that a force produces.

11. An object that has kinetic energy must be
(a) falling.
(b) moving.
(c) at an elevated position.
(d) at rest.
(e) none of these.

12. Do 100 J of work in 50 s and your power output is
(a) 1/4 W.
(b) 1/2 W.
(c) 2 W.
(d) 4 W.
(e) more than 4 W.

13. Put a pipe over the end of a wrench when trying to turn a stubborn nut on a bolt, to effectively make the wrench handle twice as long, you'll multiply the torque by
(a) two.
(b) four.
(c) eight.

14. A car travels in a circle with constant speed. The net force on the car is
(a) zero because the car is not accelerating.
(b) directed towards the center of the curve.
(c) directed forward, in the direction of travel.
(d) none of these.

15. The reason the moon does not crash into the earth is that the
(a) moon has less mass than the earth.
(b) earth's gravitational field is weak at the moon.
(c) gravitational pull of other planets keeps the moon up.
(d) moon has a sufficient tangential speed.
(e) none of these.

Need more examples or assistance? If you have a new text book then you may be able to access tutorials and online quizes at www.PhysicsPlace.com. The Access Code for this site is normally included in the first few pages of the book. See Dr. B for help during these office hours.

Your Name:	e.g. John Doe
Your Campus ID:	e.g. 12345678
Your SFA Email Address:	e.g. doejd@titan.sfasu.edu
Due Date	12/7/2007 5:00PM

0. Some of the questions below may have been modified from the in-class handout. Try to answer these first without looking at the handout, then study the handout, modify your answers if necessary and click Submit. I understand I do not understand
	1. Inside a freely-falling elevator, there would be no (a) gravitational force on you. (b) apparent weight for you. (c) both of these (d) none of these
	2. Which is most responsible for the ocean tides? (a) ships (b) continental drift (c) the moon (d) the sun
	3. Padded dashboards in cars are safer in an accident than nonpadded ones because an occupant hitting the dash has (a) increased time of impact. (b) decreased impulse. (c) decreased impact force. (d) a and b above. (e) a and c above.
	4. Two identical gliders slide toward each other on an air track. One moves at 1 m/s and the other at 2 m/s. They collide and stick. The combined mass moves at (a) 3/4 m/s. (b) 1/3 m/s. (c) 1/6 m/s. (d) 1/2 m/s. (e) 1.5 m/s.
	5. A 5-kg fish swimming at a speed of 1 m/s swallows an absent-minded 1-kg fish at rest. The speed of the larger fish after lunch is (a) 1/2 m/s. (b) 2/5 m/s. (c) 5/6 m/s. (d) 6/5 m/s. (e) 1 m/s.
	6. A moving object on which no forces are acting will continue to move with constant (a) impulse. (b) momentum. (c) acceleration. (d) all of these (e) none of these.
	7. When you are in the way of a fast-moving object and can't get out of its way, you will suffer a smaller force of impact if you decrease its momentum over a (a) short time. (b) long time. (c) same way either way.
	8. When you jump from an elevated position you usually bend your knees upon reaching the ground. By doing this, you make the time of the impact about 10 times as great as for a stiff-legged landing. In this way the average force your body experiences is (a) less than 1/10 as great. (b) about 1/10 as great. (c) about 10 times as great. (d) more than 1/10 as great.
	9. If you push an object with twice the work input for twice the time, your power input is (a) four times as much. (b) twice. (c) the same amount as for half the work in half the time.
	10. Whereas impulse involves the time that a force acts, work involves the (a) time and distance that a force acts. (b) distance that a force acts. (c) acceleration that a force produces.
	11. An object that has kinetic energy must be (a) falling. (b) moving. (c) at an elevated position. (d) at rest. (e) none of these.
	12. Do 100 J of work in 50 s and your power output is (a) 1/4 W. (b) 1/2 W. (c) 2 W. (d) 4 W. (e) more than 4 W.
	13. Put a pipe over the end of a wrench when trying to turn a stubborn nut on a bolt, to effectively make the wrench handle twice as long, you'll multiply the torque by (a) two. (b) four. (c) eight.
	14. A car travels in a circle with constant speed. The net force on the car is (a) zero because the car is not accelerating. (b) directed towards the center of the curve. (c) directed forward, in the direction of travel. (d) none of these.
	15. The reason the moon does not crash into the earth is that the (a) moon has less mass than the earth. (b) earth's gravitational field is weak at the moon. (c) gravitational pull of other planets keeps the moon up. (d) moon has a sufficient tangential speed. (e) none of these.