If a car takes a banked curve at less than a given speed, friction is needed to keep it from sliding toward the inside of the cu
rve (a real problem on icy mountain roads). (a) Calculate the minimum speed, in meters per second, required to take a 84 m radius curve banked at 16° so that you don't slide inwards, assuming there is no friction. (b) What is the minimum coefficient of friction needed for a frightened driver to take the same curve at 16 km/h?
2 answers:
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Answer:
the third piece landed meters in a direction 45 degrees from the observer's right towards the front
Explanation:
Due to conservation of momentum, the momentum of the third piece must add to the other two momenta in vector from to render zero (initial momentum of the firework on a plane parallel to ground. Therefore the momentum components of the third piece must have a component to the right equal in magnitude to the momentum of the piece that traveled to the left, and a momentum component pointing to the front of the observer of equal magnitude to that of the piece that traveled behind the observer. Then the direction of the third momentum must be at 45 degrees from the observer's right towards the observer's front.
Also, the magnitude of a momentum vector of such components, is given by the Pythagorean theorem. Recall also that the magnitudes of the momentum vectors of the first two pieces must be equal since they traveled equal distances.
Then the distance traveled by the third piece must also keep this proportionality:
The question is incomplete. Here is the complete question.
Cars A nad B are racing each other along the same straight road in the following manner: Car A has a head start and is a distance beyond the starting line at t = 0. The starting line is at x = 0. Car A travels at a constant speed
. Car B starts at the starting line but has a better engine than Car A and thus Car B travels at a constant speed
, which is greater than
.
Part A: How long after Car B started the race will Car B catch up with Car A? Express the time in terms of given quantities.
Part B: How far from Car B's starting line will the cars be when Car B passes Car A? Express your answer in terms of known quantities.
Answer: Part A:
Part B:
Explanation: First, let's write an equation of motion for each car.
Both cars travels with constant speed. So, they are an uniform rectilinear motion and its position equation is of the form:
where
is initial position
v is velocity
t is time
Car A started the race at a distance. So at t = 0, initial position is .
The equation will be:
Car B started at the starting line. So, its equation is
Part A: When they meet, both car are at "the same position":
Car B meet with Car A after units of time.
Part B: With the meeting time, we can determine the position they will be:
Since Car B started at the starting line, the distance Car B will be when it passes Car A is units of distance.