Answer:
You pull on the oars. By the third law, the oars push back on your hands, but that’s irrelevant to the motion of the boat. The other end of each oar (the blade) pushes against the water. By the third law, the water pushes back on the oars, pushing the boat forward.
B. Starting with most recent
Q: ken, 0.75 kg, moves toward a wall (his path normal to the wall) at 52 m/s. 13.0 ms after he touches the wall he pushes himself off in the opposite direction at 60 m/s. What is the magnitude of the average force the wall exerts on Ken during this rapid maneuver
Answer:
-6461.54 N
Explanation:
From Newton's Fundamental equation,
F = m(v-u)/t.................... Equation 1
Where F = Force exerted in sonic, m = mass of ken, v = final velocity, u = initial velocity, t = time.
Given: m = 0.75 kg, v = - 60 m/s (opposite direction), u = 52 m/s, t = 13 ms = 0.013 s
Substitute into equation 1
F = 0.75(-60-52)/0.013
F = 0.75(-112)/0.013
F = -84/0.013
F = -6461.54 N
Note: The negative sign tells that the force act in opposite direction to the initial motion of ken.
Hence the magnitude of the average force of the wall = -6461.54 N
Additionally, the coefficient of thermal expansion of the restorative material should be comparable to the coefficient of thermal expansion of the tooth structure, since a significant difference between the two could result in thermal-induced stress at the cavity wall and subsequent marginal failure.
This study's objective was to assess how thermal stress affected the marginal integrity of restorative materials with various adhesive and thermal characteristics. As an alternative to clinical trials, which are expensive and time-consuming, evaluation of restorative materials under laboratory simulations of clinical function is frequently carried out. Thermal cycling regimens, which are in vitro techniques that subject the restoration and the tooth to extremely high temperatures, are frequently used in laboratory simulations to replicate thermal stresses that naturally occur in vivo.
Learn more about Thermal Stress here-
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