1. You are loading a spring loaded dart gun and do an amount of work W such that the spring is only 1/3 compressed. How much additional work must you do to fully compress it from 1/3 to fully compressed? Answer in terms of W.
2. A large man tosses a small child onto a large pile of leaves. During the toss, the man exerts _________ force (magnitude) on the child as compared to the force the child exerts on him while the acceleration (magnitude) of the man is _________ than the child's.
a. a larger & smaller.
b. the same & smaller.
c. the same & the same.
d. a larger & the same.
3. Two bodies are falling with negligible air resistance, side by side, above flat, horizontal ground. If one of the bodies is given an additional horizontal acceleration during its descent, it:
a. strikes the ground at the same time as the other body
b. has the vertical component of its acceleration altered
c. strikes the ground earlier than the other body
d. follows a straight line path along the resultant acceleration vector
e. has the vertical component of its velocity altered
1. Work done in compressing the spring gets stored as the potential energy of the spring. PE stored in a spring of spring constant k, compressed to a length x from its normal position is given by ½ kx^2.
When compressed L/3, PE of the spring = ½ k(L/3)^2 = kL^2/18 = W
When fully ...
The following posting answers questions regarding classical mechanics.
Classical Mechanics - Speed of a Ferry and Parabolic Curve of a ball
A ferry can travel at an optimal speed of 8 km/h in still water measured relative to the shore. What is the optimal speed of the ferry, relative to the shore, if it moves perpendicular to a 6 km/h current?
A 4 km/h
B 8 km/h
C 10 km/h
D 14 km/h
E 28 km/h
A baseball is hit upward and travels along a parabolic arc before it strikes the ground. Which one of the following statements is necessarily true?
A The acceleration of the ball decreases as the ball moves upward.
B The velocity of the ball is zero m/s when the ball is at the highest point in the arc.
C The acceleration of the ball is zero m/s2 when the ball is at the highest point in the arc.
D The x-component of the velocity of the ball is the same throughout the ball's flight.
E The velocity of the ball is a maximum when the ball is at the highest point in the arc.