1. A bicyclist and a parked car have a head-on collision. Compare the relative motions on each.
2. Why isn't the Earth pulled into orbit around a communication satellite?
assuming they stick to each other
mass bike * v bike = (mass of bike+car) * ( v of bike+car)
since mass of bike+car is huge compared to mass of bike, the end velocity is tiny
It is, but the radius of the orbit of earth due to satellite is miniscule compared to the orbit radius of the satellite around earth
force of each on the other the same G Mearth Msat /d^2
inward acceleration * mass of each = that force =
m * orbit radius *omega^2
if m is huge, orbit radius is tiny
A better way to say it is that both orbit around the center of mass of satellite earth system However that is very close to earth center because of the huge difference in mass.
1. In order to compare the relative motions of the bicyclist and the parked car, we need to consider the concept of inertia.
When a head-on collision occurs between a moving object (in this case, the bicyclist) and a stationary object (the parked car), both objects experience forces. According to Newton's first law of motion, an object at rest tends to stay at rest, and an object in motion tends to stay in motion with the same speed and in the same direction unless acted upon by an external force.
In this scenario, the parked car experiences a sudden external force caused by the collision with the bicyclist. It will likely start moving in the direction of the impact, assuming no external factors (e.g., emergency brake) prevent it from doing so. The direction and speed of the car's subsequent motion will depend on the mass of the car, the magnitude of the force applied during the collision, and any other forces acting on it (e.g., friction or air resistance).
On the other hand, the bicyclist will also experience a force due to the collision. Depending on the mass, speed, and angle of collision, the bicyclist could either be thrown forward, backward, or sideways, depending on the impact forces involved. The direction and speed of the bicyclist's subsequent motion will depend on these factors and any other forces acting on them (e.g., the friction between the tires and the road).
In summary, both the bicyclist and the parked car will experience a change in motion due to the collision. The extent and nature of that change will depend on various factors, including the masses of the objects, the forces involved, and any external factors affecting their motion.
2. The reason the Earth isn't pulled into orbit around a communication satellite is due to the interplay between the gravitational force and centripetal force.
When an object is in orbit, it is constantly falling towards the Earth due to the gravitational force, but it also has a sufficient tangential velocity to keep missing the Earth. This motion creates a state of perpetual free fall, resulting in a stable orbit.
In the case of a communication satellite orbiting the Earth, the satellite is moving at a high speed horizontally to maintain its orbit. The gravitational force exerted by the Earth pulls the satellite inward, attempting to make it fall towards the Earth. However, the tangential velocity of the satellite counteracts this pull, resulting in a balance between gravitational force and centripetal force.
In other words, the satellite's horizontal speed keeps it in a constant state of 'falling,' which, coincidentally, matches the curvature of the Earth. This allows the satellite to continuously orbit around the Earth without being pulled directly into it.
It's important to note that achieving and maintaining an orbit requires precise calculations and adjustments in order to balance the gravitational force and the centripetal force. Communication satellites, for example, are placed in specific orbits where their speed and altitude are carefully calibrated to ensure they remain in orbit without being dragged down to the Earth's surface.