As part of your daily workout, you lie on your back and push with your feet against a platform attached to two stiff springs arr
1 answer:
Answer:
a) F = 680 N, b) W = 215 .4 J , c) F = 1278.4 N
Explanation:
a) Hooke's law is
F = k x
To find the displacement (x) let's use the elastic energy equation
= ½ k x²
k = 2 / x²
k = 2 85.0 / 0.250²
k = 2720 N / m
We replace and look for elastic force
F = 2720 0.250
F = 680 N
b) The definition of work is
W = ΔEm
W = -
W = ½ k ( ² - x₀²)
The final distance
= 0.250 +0.220
= 0.4750 m
We calculate the work
W = ½ 2720 (0.47² - 0.25²)
W = 215 .4 J
We calculate the strength
F = k
F = 2720 0.470
F = 1278.4 N
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The initial velocity of the ball is 1.01 m/s
Explanation:
The motion of the ball rolling off the desk is a projectile motion, which consists of two independent motions:
- A uniform horizontal motion with constant horizontal velocity
- A vertical accelerated motion with constant acceleration (, acceleration due to gravity)
We start by analyzing the vertical motion: we can find the time of flight of the ball by using the following suvat equation
where
s = 1.20 m is the vertical displacement (the height of the desk)
u = 0 is the initial vertical velocity
t is the time of flight
Solving for t,
Now we analyze the horizontal motion. We know that the ball covers a horizontal distance of
d = 0.50 m
in a time
t = 0.495 s
Therefore, since the horizontal velocity is constant, we can calculate it as
So, the ball rolls off the table at 1.01 m/s.
Learn more about projectile motion:
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