Answer:
390 J
Explanation:
m = 3 kg
u = 16 i + 2 j
(a) Magnitude of velocity =
= 16.1245 m/s
KEi = 1/2 m v^2 = 0.5 x 3 x 16.1245 = 390 J
(b) v = 18 i + 14 j
Magnitude of velocity =
= 22.804 m/s
KEf = 1/2 m v^2 = 0.5 x 3 x 22.804 = 780 J
According to the work energy theorem
Work done = change in KE = KEf - KEi = 780 - 390 = 390 J
Answer:
39.2m/s
Explanation:
Given parameters:
Mass of book = 5kg
Time taken for fall = 4s
Unknown:
Final velocity of the book = ?
Solution:
Serena dropped the book from rest therefore, the initial velocity of the book is 0.
Let us find the appropriate motion equation to solve this problem;
V = U + gt
V is the final velocity
U is the initial velocity
g is the acceleration due to gravity = 9.8m/s²
t is the time taken
Insert the given parameters and solve;
V = 0 + 9.8 x 4 = 39.2m/s