Answer:
87
Explanation:
despite experiencing a 60N drag. Neglect any friction
impeding her motion.
How many forces are acting on the bicyclist?
What is the magnitude of the net force on the bicyclist?
How much force is the bicyclist generating through her
pedaling?
a) 4 forces
b) 186 N
c) 246 N
Explanation:
a)
Let's count the forces acting on the bicylist:
1) Weight (): this is the gravitational force exerted on the bicyclist by the Earth, which pulls the bicyclist towards the Earth's centre; so, this force acts downward (m = mass of the bicyclist, g = acceleration due to gravity)
2) Normal reaction (N): this is the reaction force exerted by the road on the bicyclist. This force acts vertically upward, and it balances the weight, so its magnitude is equal to the weight of the bicyclist, and its direction is opposite
3) Applied force (): this is the force exerted by the bicylicist to push the bike forward. Its direction is forward
4) Air drag (): this is the force exerted by the air on the bicyclist and resisting the motion of the bike; its direction is opposite to the motion of the bike, so it is in the backward direction
So, we have 4 forces in total.
b)
Here we can find the net force on the bicyclist by using Newton's second law of motion, which states that the net force acting on a body is equal to the product between the mass of the body and its acceleration:
where
is the net force
m is the mass of the body
a is its acceleration
In this problem we have:
m = 60 kg is the mass of the bicyclist
is its acceleration
Substituting, we find the net force on the bicyclist:
c)
We can write the net force acting on the bicyclist in the horizontal direction as the resultant of the two forces acting along this direction, so:
where:
is the net force
is the applied force (forward)
is the air drag (backward)
In this problem we have:
is the net force (found in part b)
is the magnitude of the air drag
Solving for , we find the force produced by the bicyclist while pedaling:
The speed of the car is 75 km/h
These are the formulas that we have to remember before solving the problem.
Speed is the rate of change of distance.
v = speed ( m/s )
d = distance ( m )
t = time ( s )
Acceleration is the rate of change of velocity.
a = acceleration ( m/s² )
Δv = change in speed ( m/s )
t = time ( s )
Let us now tackle the problem!
Given:
distance = d = 150 km
time taken = t = 7200 s = 2 hours
Unknown:
velocity = v = ?
Solution:
The acceleration of the car is 0 m/s² because it travels with constant speed.
We could also plot the distance vs time graph as shown in the attachment.
Grade: Middle School
Subject: Physics
Chapter: Kinematics
Keywords: indycar top speed of a fastest police car has ever gone
The car's speed is 75 km/hour, as determined by dividing the total distance travelled (150 km) by the total time taken (2 hours).
To answer this question, we use the
formula for speed
, which is distance traveled divided by the time taken. Here, the distance travelled by the car is 150 km and the time taken is 7200 s (which is equal to 2 hours). Therefore, the speed will be 150 km divided by 2 hours, resulting in a speed of
75 km/hour
, stated to the correct number of significant figures.
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The phrase "by ordinary means" was added to the Law of Conservation of Energy because kind to be expected in the normal order of events.
The phrase "by ordinary means" was added The phrase "by ordinary means" was added.
To learn more about laws of conservation of energy refer:brainly.com/question/11911812
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-it can only be converted from one form to another.
Stratus
Cumulus
Stigform