a 1 kg ball is thrown upwards with a speed of 9.9 m/s calculate the work done by its Weight in one second
Answers
Answer:
-49J
Explanation:
Given:-
⋄ Mass of ball =1 kg
⋄ Initial velocity of ball (u) = 9.9m/s
⋄ Acceleration due to gravity (g) = 9.8m/s²
⋄ Time taken (t) = 1 s
✰To Find :-
⋄ Work done by its weight???
✰Solution :-
➧ The distance moved in One second is
\begin{gathered}s = ut + \frac{1}{2} gt {}^{2} \\ \\ s = 9.9 \times 1 + \frac{1}{2} \times 9.8 \times 1 {}^{2} \\ \\ s = 5m\end{gathered}
s=ut+
2
1
gt
2
s=9.9×1+
2
1
×9.8×1
2
s=5m
The weight of the ball is (mg) = 1×9.8 =9.8 N in the downward direction.
➧ Work done in one second = (-9.8)×5=-49J.
∴The work done by its weight is -49 J
Given : a 1 kg ball is thrown upwards with a speed of 9.9 m/s
To Find : calculate the work done by its Weight in one second
Solution:
Initial Velocity = 9.9 m/s
a = g = - 9.8 m/s
V = U + at
Velocity after 1 sec = 9.9 + (-9.8)(1)
= 0.1 m/s
KE = Kinetic Energy
KE = (1/2)mV²
KE at initial = (1/2)*1(9.9)²
KE after 1 sec = (1/2)*1(0.1)²
Change in KE = (1/2)*1(0.1)² - (1/2)*1(9.9)²
= (1/2) ( 0.1 + 9.9)(0.1 -9.9)
= (1/2)(10)(-9.8)
= -49 J
Work Done = -49 J
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