A school bus moves past a parked car at a speed of 30 km/hr. Which of the following BEST describes the observation made by a pas
1 answer:
Answer:
C.The car appears to be moving 30 km/hr in the opposite direction of the bus.
Explanation:
There are two reference systems involved in this situation:
- Reference system S: this is the reference system where velocities are measured with respect to the ground. In this reference system, the car is parked, so its velocity is
- Reference system S': this is the reference system moving with the bus. This reference system is moving with a velocity of with respect to the reference system S
Calling the velocity of the car in the reference system S', we have:
From which
and the negative sign means that a passanger in the bus observes the car moving in the opposite direction.
You might be interested in
To increase the centripetal acceleration to , you can double the speed or decrease the radius by 1/4
Explanation:
An object is said to be in uniform circular motion when it is moving at a constant speed in a circular path.
The acceleration of an object in uniform circular motion is called centripetal acceleration, and it is given by
where
v is the speed of the object
r is the radius of the circular path
In the problem, the original centripetal acceleration is
We want to increase it by a factor of 4, i.e. to
We notice that the centripetal acceleration is proportional to the square of the speed and inversely proportional to the radius, so we can do as follows:
- We can double the speed:
v' = 2v
This way, the new acceleration is
so, 4 times the original acceleration
- We can decrease the radius to 1/4 of its original value:
So the new acceleration is
so, the acceleration has increased by a factor 4 again.
Learn more about centripetal acceleration:
#LearnwithBrainly