s = s_i + v_i t + (¹/₂) a t²
v = v_i + a t
v² = v_i² + 2 a (s - s_i)
sin = ^opp/_hyp
cos = ^adj/_hyp
tan = ^opp/_adj
F = m a
F₁₂ = – F₂₁
f_s,max = µ_s n
f_k = µ_k n
g = 9.8 m/s² 10 m/s²

1. Concept Questions:

a) Galileo first clearly understood motion. Galileo may be described as the Father of Modern Science. Why is that?

People had talked about or discussed motion long before Galileo, of course. Even the ancient Greeks had talked and thought and taught about motion. But Galileo is the first person who went out and conducted experiments and looked to see if his predictions agreed with experimentally measureable results.

This is the "hallmark" or "chief characteristic" of modern science -- that any theory must agree with experimental results if it is to be believed.

b) What are Newton’s Three Laws of Motion?
i) In the absence of a net force, a body at rest will remain at rest and a body in motion will continue in motion along the same straight line with the same velocity.


ii) F = m a; If there is a net force on an object, it will accelerate with an acceleration in the direction of the net force and with an acceleration proportional to the net force and inversely proportional to the mass (a = F / m).


iii) F₁₂ = - F₂₁




c) If a block is sitting at rest on a level surface, what is the friction force on the block?

Since there is no external force with a horizontal component, the Friction force is also zero.

d) A newton (N) is a unit of force. In terms of kg, m, and s, what is 1 N?

1 N = ?

F = m a

1 N = (1 kg) (1 m/s²)

1 N = 1 kg-m/s²

3. A ball is thrown from a third-floor balcony, 7.0 m above the parking lot below. The ball is thrown with an initial velocity of 10.0 m/s, at an angle of 37° above the horizontal.
a) What are the horizontal and vertical components of its initial velocity?
b) How long is the ball in the air, before it strikes the parking lot below?
c) How far from the building does it strike the parking lot below?

4. A 3 kg block sits on a smooth (frictionless) plane inclined 20° above the horizontal. It is connected by a string to a 5 kg mass that hangs suspened from the other end of the string as shown in the sketch above.
a) Draw large, clear, complete “free-body” diagrams showing all the forces on the two masses.
b) Apply Newton’s Second Law, F = m a, to the two masses and find the acceleration of the system and the tension in the string.

5. A 2-kg block slides down a plane inclined at 20° from the horizontal as shown in the diagram above. The coefficient of sliding friction between the block and the plane is µ = 0.2.
a) Make a large, good, clear, complete “free-body diagram” showing all the forces on the 2-kg mass.
b) Apply Newton’s Second Law, F = m a, to the mass and find the acceleration of the block down the inclined plane.
c) How fast will the block be moving when it has traveled 1.0 m down the plane?