Science
1 answer:
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Answer:
Explanation:
When a projectile is fired upwards with some initial speed then the it reaches the top of the projectile and then falls back to the ground.
According to the question we need to find the work done by the gravity which is acting downwards for the projectile when it is at a position just about to hit the ground in course of falling down.
As we know that work is given as:
here:
force of gravity on the object (which is acting downwards)
displacement of the object
- Here the work done by the gravity at an instant just before the projectile hits the earth will be negative as the displacement is in the direction opposite to the force of gravity.
Answer:
a) 37171
b) sec
Explanation:
m = mass of the weight being lifted = 60.0 kg
d = distance by which the weight is lifted = 0.670 m
E = Energy available to burn = 1 lb = 3500 kcal = 3500 x 4184 J
g = acceleration due to gravity = 9.8 m/s²
n = number of times the weight is lifted
Energy available to burn is given as
E = n m g d
3500 x 4184 = n (60) (9.8) (0.670)
n = 37171
b)
T = time period for each lift up = 1.80 s
t = total time taken
Total time taken is given as
sec