velocity and acceleration

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 passenger on the bus?

• The car appears to be moving 30 km/hr in the same direction as the bus.

• The car appears to be moving 30 km/hr in the opposite direction of the bus.

• The car appears to be moving 15 km/hr in the same direction as the bus.

• The car appears to be moving 15 km/hr in the opposite direction of the bus.

A student investigated motion by alternately traveling up two different elevators in a 5-floor

building. The first elevator had a large window to the outside of the building while the second

elevator was enclosed. The student sensed more upward motion in the first elevator even

though both elevators traveled at the same rate. Why did the student sense more motion in

the elevator with the window?

• Glass elevators have greater air currents than enclosed elevators, creating a sense of upward

  motion.

• Outdoor objects appear to move down while the glass elevator goes up, creating a sense of

  upward motion.

• The weight of the glass elevator compared to the enclosed elevator creates a sense of upward

  motion.

• The glass elevator has more sunlight than the enclosed elevator, creating a sense of upward

  motion.

A boat was traveling at 15 mph when a passenger threw an object at 10 mph in the same

direction the boat was moving. A friend, standing on the shore, observed the object moving

with a speed of 25 mph. The passenger observed the object moving with a speed of 10 mph.

Why were the two observations different?

• The current of the river affects the speed of the boat relative to shore.

• Objects appear to move more slowly when they move away from the observer.

• The passenger and the friend were watching the object from two different frames of reference.

• The distance between the boat and the shore gave the friend a different viewing angle.

Over a period of 2.50 seconds, a speedboat accelerates uniformly from 18.5 m/s to 46.5 m/s.

What is the acceleration of the speedboat relative to the shore?

• –28 m/s^2

• 28 m/s^2

• –11.2 m/s^2

• 11.2 m/s^2

Tags

NGSS.HS-PS2-1

An airplane was moving 50 m/s to the north relative to the air at landing. The wind was

blowing 5 m/s toward the south relative to the ground. What was the speed of the airplane

relative to the ground at the time of landing?

• 10 m/s

• 45 m/s

• 55 m/s

• 250 m/s

During liftoff, a space shuttle accelerated to a speed of 862 m/s in 75 seconds. What was the

average acceleration of the astronauts in the space shuttle with respect to the shuttle during

liftoff?

• 0 m/s^2

• 9.8 m/s^2

• 11.5 m/s^2

• 19.6 m/s^2

Tags

NGSS.HS-PS2-1

A boat is moving at a speed of 7 m/s relative to the water. A dog walks from the front to the

back of the boat at a speed of 2 m/s relative to the boat. What is the speed of the dog, in

m/s, relative to the water?

• 3.5 m/s

• 5 m/s

• 9 m/s

• 14 m/s

A boat travels north at a rate of 25 kilometers per hour (km/hr) relative to the current of the

river. The current of the river moves south at a rate of 10 km/hr relative to the ground.

What is the rate of motion of the boat relative to the ground?

• 10 km/hr south

• 15 km/hr north

• 25 km/hr south

• 35 km/hr north

A passenger jet flies at an average speed of 600 miles per hour (mph) east. A satellite orbits

Earth at about 17,500 mph, west to east. If the pilot of the jet sees the satellite passing

directly overhead, how fast will the satellite appear to be moving?

• 600 mph

• 16,900 mph

• 17,500 mph

• 18,100 mph

Dave is walking from the back of a train to the front of the train at a rate of 6 kilometers per

hour (km/hr). The train is traveling at a rate of 42 km/hr. What is Dave’s speed, relative to

the ground?

• 7 km/hr

• 36 km/hr

• 48 km/hr

• 252 km/hr