4 The approximate velocity-time graph for a car on a 5-hour journey is shown in Figure 3.8. (There is a very quick driver
change midway to prevent driving fatiguel)
a State in which of the regions OA, AB, BC, CD, DE the
car is (i) accelerating, (ii) decelerating, (iii) travelling
with uniform velocity
b Calculate the value of the acceleration, deceleration or
constant velocity in each region.
c What is the distance travelled over each region?
d What is the total distance travelled?
e Calculate the average velocity for the whole journey.
C D
100
А
B
80
speed/kmh)
60
40
20
o
E
o
0
4
5
2 3
time/hours

Part f - example: finding two forces (part i) two dimensional dynamics often involves solving for two unknown quantities in two separate equations describing the total force. the block in (figure 1) has a mass m=10kg and is being pulled by a force f on a table with coefficient of static friction îľs=0.3. four forces act on it: the applied force f (directed î¸=30â above the horizontal). the force of gravity fg=mg (directly down, where g=9.8m/s2). the normal force n (directly up). the force of static friction fs (directly left, opposing any potential motion). if we want to find the size of the force necessary to just barely overcome static friction (in which case fs=îľsn), we use the condition that the sum of the forces in both directions must be 0. using some basic trigonometry, we can write this condition out for the forces in both the horizontal and vertical directions, respectively, as: fcosî¸â’îľsn=0 fsinî¸+nâ’mg=0 in order to find the magnitude of force f, we have to solve a system of two equations with both f and the normal force n unknown. use the methods we have learned to find an expression for f in terms of m, g, î¸, and îľs (no n).

How many times did thomas edison mess up the light bulb

The california mussel (mytilus californianus) attaches itself to a rock or other solid surface with a bundle of filaments known as the byssus. imagine that 15.0 j of work is done to stretch the distal end of the byssus. it releases 10.8 j of thermal energy as it relaxes. what is the resilience of the distal end of the byssus?