Answer:
(A) 667.5 N/m
(B)
Explanation:
(A) Let the spring constant be k.
Using the formula F = kx
k = 251 / 0.376
K = 667.5 N/m
(B)
Work done
W = 0.5 × kx^2
W = 0.5 × 667.5 × 0.376 × 0.376
W = 47.2 J
Answer:
The moment of inertia decreased by a factor of 4
Explanation:
Given;
initial angular velocity of the ice skater, ω₁ = 2.5 rev/s
final angular velocity of the ice skater, ω₂ = 10.0 rev/s
During this process we assume that angular momentum is conserved;
I₁ω₁ = I₂ω₂
Where;
I₁ is the initial moment of inertia
I₂ is the final moment of inertia

Therefore, the moment of inertia decreased by a factor of 4
Answer:
The statement is not correct.
Explanation:
To know if the statement is correct, we shall determine the velocity of the car after 3 s. This is illustrated below.
Data obtained from the question include:
Initial velocity (u) = 0 m/s
Acceleration due to gravity (g) = 9.8 m/s²
Time (t) = 3 s
Final velocity (v) =?
v = u + gt
v = 0 + (9.8 × 3)
v = 0 + 29.4
v = 29.4 m/s
Thus, the velocity of the car after 3 s is 29.4 m/s.
Hence, the statement made by the friend is not correct as the car has a falling velocity of 29.4 m/s after 3 s.