A large plate is fabricated from a steel alloy that has a plane strain fracture toughness of 82.4 mpa1m (75.0 ksi1in.). if the p
1 answer:
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Answer:
a) k= 3594,7 N/m
b) v= 0.55 m/s
Explanation:
- a)
- As the surface is horizontal, the only change in energy will be the change in kinetic energy, as the box comes to an stop after compressing the spring.
- As we know that the surface is frictionless also, this change in kinetic energy must be equal to the change in the elastic potential energy of the spring.
- So we can write the following equality:
where
and
- Simplifying and replacing by the values, we get:
- Solving for k:
- k = 3594.7 N/m
- b)
- For this part, we can just apply the same equality, replacing the value of k by the one we got, and solving for the initial speed v:
- v = 0.55 m/s
Answer:
b. The side the boy is sitting on will tilt downward
Explanation:
Initially, the seesaw is balanced because the torque exerted by the boy is equal to the torque exerted by the girl:
where
Wb is the weight of the boy
db is the distance of the boy from the pivot
Wg is the weight of the girl
dg is the distance of the girl from the pivot
When the boy moves backward, the distance of the boy from the pivot ( increases, therefore the torques are no longer balanced: the torque exerted by the boy will be larger, and therefore the side of the boy will tilt downward.