Một cái đĩa có bán kính R quay quanh trục vuông góc và đi qua tâm đĩa theo phương trình ϕ = at3 + bt2 + c;Tìm gia tốc tiếp tuyến
2 answers:
You might be interested in
a)
b) 964.5 N
c) 0.069
Explanation:
a)
When an object is moving in a circular motion, the direction of its velocity is changing - therefore, it has an acceleration towards the center of the circle, called centripetal acceleration.
The magnitude of the centripetal acceleration is given by
where
v is the speed of the object
r is the radius of the circle
For the car in this problem:
v = 40.0 km/h = 11.1 m/s is the speed
r = 180 m is the radius of the circle
Substituting, we find the acceleration:
b)
The centripetal force is the force that keeps the object along its circular motion. It also acts towards the center of the circle, and it is given by
where
m is the mass of the object
a is the centripetal acceleration
Here the weight of the car is
where
is the acceleration due to gravity
So the mass is
Therefore, the centripetal force is
c)
In this case, the force of static friction between the tires and the road provides the required centripetal force to keep the car in circular motion. This force is given by:
where
is the coefficient of friction
Equating the frictional force to the centripetal force,
So we get:
And substitutng:
(centripetal acceleration)
We find: