What is the net force acting on the bookcase

Assignment Help Physics

Reference no: EM13803960

Part -1:

1) Find the net force produced by a 30-N force and a 20-N force in each of these cases:

(a) Both forces act in the same direction.

(b) The two forces act in opposite directions.

2) A horizontal force of 120N is required to push a bookcase across a floor of constant velocity

(a) What is the net force acting on the bookcase?

(b) How much is the friction force that acts on the sliding bookcase?

3) (a) Show the average speed of a tennis ball is 48 m/s when it travel the full length of the court, 24m in 0.5 s.

4) (a) Show the average speed that the average speed of Leslie is 10 km/h when she runs to the store 5km away in 30min

5) (a) Show that the acceleration is 7.5 m/s for a ball that starts from rest and rolls down a ramp and gains a speed of 30 m/s in 4s.
Exercise 91

For a freely falling object dropped from rest, what is acceleration at the end of 5s.

Discussion Questions

6) Henry the painter swings year after year from his bosun's chair. His weight is 500N and the rope unknown to him has a breaking point of 300N. Why doesn't the rope break when he is supported shown on the left? One day Harry was painting near a flagpole for a change, he tied the free end of the rope to the flagpole instead of his chair as shown right. Discuss with your friend why Harry took his vacation early.

7) Two balls A and B are released simultaneously from rest at left end of equal-length tracks, as shown. Which ball, A or B, will reach the end of the track first?

8) Refer to the preceding question.

(a) Does ball B roll faster along the lower part of its track than ball A along its straighter track?

(b) Is the speed gained by ball B going down the extra dip the same as the speed it loses going up near the right hand end --- and doesn't this mean that the speeds of balls A and B will be the same at both ends of the tracks?

(c) For ball B won't the average speed dipping down and up be greater than the average speed of ball A during the same time?

(d) So overall does ball A or B have the greater average speed? ( Do wish to change you answer to the preceding question?)

Part -2:

9. An astronaut of mass 120 kg recedes from her spacecraft by activating a small propulsion unit attached to her back. The force generated by a spurt is 30 N. Show that her acceleration is 0.25 m/s².

10. Sophia exerts a steady 40-N horizontal force on a 8-kg box resting on a lab bench. The box slides against a horizontal friction force of 24 N. Show that the box accelerates at 2 m/s²

11. A rocket of mass 100,000 kg undergoes an acceleration of 2 m/s². Show that the net force acting on it is 200,000 N

12. If it were not for air resistance, would it be dangerous to go outdoors on rainy days? Defend your answer

Disscusion Question

13. On which of these hills does the ball roll down with increasing speed and decreasing acceleration along the path? (Use this example if you wish to explain to someone the difference between speed and acceleration.)

14. If you drop an object, its acceleration toward the ground is 10 m/s². If you throw it down instead, will its acceleration after leaving your hand be greater than 10 m/s2? Ignore air resistance. Defend your answer.

15. Can you think of a reason why the acceleration of the object thrown downward through the air in the preceding question would actually be less than 10 m/s²?

Reference no: EM13803960

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