Relative Motion

Galileo came up with the concept that different points of view would observe motion in different ways. Imagine that a ball is being dropped from the mast of a boat, what would the path of the ball be from a bystander on the shore?

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Tags

NGSS.MS-PS2-1

NGSS.MS-PS2-2

NGSS.MS-PS2-4

A car traveling at the legal speed limit has velocity +V with respect to the road. You are in another car traveling in the opposite direction at the legal speed limit with respect to the road. As the first car approaches you, what is its velocity relative to you?

• +V

• 0

• +2V

• -2V

A passenger on a bus moving east sees a man standing on a pavement. From the passenger’s perspective, the man appears to

• Stand still.

• Move west at a speed that is less than the bus’ speed.

• Move west at a speed that is equal to the bus’ speed.

• Move east at a speed that is equal to the bus’ speed.

A rhinoceros is moving west at a velocity of 1 m/s with a tickbird on its back. The tickbird walks east at a velocity of 0.25 m/s relative to the rhinoceros. At what velocity is the tickbird traveling with respect to the photographer?

• 1.25 m/s west

• 1.25 m/s east

• 0.75 m/s west

• 0.75 m/s east

An airplane flies in a straight level line at constant speed as shown. A package is to be dropped from the plane so that it hits a target at point Q.

Point P is directly over the target. When should the package be dropped?

• At a certain time before the plane reaches point P

• At the instant that the plane reaches point P

• Immediately after the plane passes point P

• Several seconds after the plane has passed point P

Tags

NGSS.MS-PS2-4

Using Car A as a frame of reference, what is the speed of Car B?

• 20 km/h

• 30 km/h

• 50 km/h

• 80 km/h

Tags

NGSS.MS-PS2-1

NGSS.MS-PS2-2

A bus is traveling north at a speed of 90 kilometers per hour (km/hr). A motorcycle traveling north at a speed of 120 km/hr passes the bus.

Which describes what the bus's motion looks like to the driver of the motorcycle?

• The bus looks like it is moving south at 30 km/hr.

• The bus looks like it is moving north at 90 km/hr.

• The bus looks like it is moving north at 120 km/hr.

• The bus looks like it is moving south at 210 km/hr.

A train 125 m long passes a man, running at 5 km/hr in the same direction in which the train is going, in 10 seconds. The speed of the train is

• 45 km/hr

• 50 km/hr

• 54 km/hr

• 55 km/hr

Tags

NGSS.MS-PS3-1

Two trains of equal length are running on parallel lines in the same direction at 46 km/hr and 36 km/hr. The faster train passes the slower train in 36 seconds. The length of each train is

• 50 m

• 75 m

• 80 m

• 85 m

Two trains A and B are moving in opposite directions with speeds of 60 km/hr and 90 km/hr respectively . Their lengths are 1.10 km and 0.9 km respectively. The time taken by the train A to cross the train B in seconds is

• 36

• 45

• 48

• 54