# A physics major is cooking breakfast when he notices that the frictional force between the steel spatula and the Dry Steel frying pan is only 0.250 N….

- Dry Steel0.2500.3

wet0.50.7

2

Yes

No

2

No

Yes

3. 50.0

Figure 4.29 (CHECK THE ATTACHMENT)

(a) Calculate the minimum force F he must exert to get the block moving.

________ N

(b) What is its acceleration once it starts to move, if that force is maintained?

_______ m/s2

4. 47.0

Figure 4.29

(a) Calculate the minimum force F he must exert to get the block moving.

________ N

(b) What is its acceleration once it starts to move, if that force is maintained?

_______ m/s2

5. 51095024.811.623.2

6. 0.5VV05-31.692

2.

No

Yes

7.

0.31085,000

9.002.30

911

70.00.850

(a) At how many rpm are the tires rotating?

______________ rpm

(b) What is the centripetal acceleration at the edge of the tire?

_______________ m/s2

(c) With what force must a determined 10-15 kg bacterium cling to the rim?

________________ N

(d) Take the ratio of this force to the bacterium’s weight.

____________ (force from part (c) / bacterium’s weight)

12. 8040.0

(a) Calculate the ideal speed to take a 105 m radius curve banked at 15°.

__________ m/s

(b) What is the minimum coefficient of friction needed for a frightened driver to take the same curve at 20.0 km/h?

14.

(a) Calculate the gravitational force exerted on a 3.00 kg baby by a 90 kg father 0.100 m away at birth (assisting so he is close).

_________ N

(b) Calculate the force on the baby due to Jupiter if it is at its closest to the earth, some 6.29 ✕ 1011 m away, showing it to be comparable to that of the father. The mass of Jupiter is about 1.90 ✕ 1027 kg. Other objects in the room and the hospital building also exert similar gravitational forces. (Of course, there could be an unknown force acting, but scientists first need to be convinced that there is even an effect, much less that an unknown force causes it.)

___________ N