1.) An 4.4 kg object gains height 6 while being accelerated from rest to a final

Question

1.) An 4.4 kg object gains height 6 while being accelerated from rest to a final speed of 6.5 m/s by an external force. What was the net work (in J) done on the object? Let g = 9.8 m/s2.

2.) A car engine delivers 3.1 * 104 W to its wheels when moving at a constant speed of 13.6 m/s. What is the magnitude of the resistive force (in N) acting on the automobile at that speed?

3.) An 2.5 kg object gains height 5.1 while being accelerated from rest to a final speed of 8.4 m/s by an external force. What was the work (in J) done on the object by this force? Let g = 9.8 m/s2.

4.) A bungee jumper jumps from a bridge. Describe what happens to the jumper's kinetic and (gravitational and elastic) potential energy right after the jumper has reached the bottom of his descent and is pulled back up?

a. kinetic energy increases, potential energy decreases

b. kinetic energy decreases, potential energy increases

c. kinetic energy increases, potential energy increases

d. kinetic energy increases, potential energy stays the same

e. kinetic energy stays the same, potential energy increases

a. kinetic energy increases, potential energy decreases

b. kinetic energy decreases, potential energy increases

c. kinetic energy increases, potential energy increases

d. kinetic energy increases, potential energy stays the same

e. kinetic energy stays the same, potential energy increases

Explanation / Answer

Please post all questions separately. Here is the answer to question#1.

(1) m = 4.4kg, h=6m, u=0, v=6.5m/s

Work done on the object W= Fh

W = mah

now we need to find acceleration a

using relation v2 - u2 = 2ah

6.52 - 0 = 2 (a) 6

a = 3.52 m/s

W = mah

W = (4.4) * (3.52) * (6)

W = 92.93 J

Related Questions

Navigate

• Browse (All)
• Browse 1
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.