Motion and Forces

An airplane leaves New York to fly to Los Angeles. It travels 3,850 km in 5.5 hours. What is the average speed of the airplane?

• 700 km

• 700 km/hr

• 700 hrs

• 700 hrs/km

The law of universal gravitation says all bodies attract each other. If you drop a cup, it falls to Earth. Why doesn’t the gravitational attraction between your hand and the cup keep the cup from falling?

• The law of universal gravitation only applies to planets in space.

• There is a gravitational attraction between you and the cup, but Earth’s gravity is stronger, so Earth’s gravity pulls the cup down

• The gravitational attraction between you and the cup is so strong that the force pushes the cup down.

• There is no gravitational attraction between you and the cup, so Earth’s gravity pulls the cup down.

The diagram below shows a satellite in orbit around Earth. It is orbiting in the direction shown and is pulled toward Earth by gravity. What would happen if Earth’s gravity suddenly disappeared?

• The satellite would continue to orbit Earth.

• The satellite would fall to Earth.

• The satellite would move into space in a straight line.

• The satellite would stop moving.

Julia is in a car with her father. The car is undergoing centripetal acceleration. What is happening to the car?

• The car is changing direction at a constant speed.

• The car is changing direction and speeding up.

• The car is stopping suddenly.

• The car is slowing down.

Rajiv made a model of a boat. When he places it in water, it sinks. According to Archimedes’ principle, why does the boat sink?

• The boat is too small.

• The buoyant force is less than the boat's weight.

• The buoyant force is equal to the boat's weight.

• The boat is made of the wrong material.

An elevator traveled 15 floors (150 ft) at a speed of 4.5 m/s. What additional information is needed to determine the velocity of the elevator?

• the direction the elevator traveled

• how long the elevator was stationary

• how many times the elevator stopped

• the total mass of the elevatro plus anything in it

In a swimming race, Miho swam the first 50 m in 42 s. She swam the second 50 m in 40 s. What was Miho’s average speed during the race?

• 0.82 m/s

• 1.19 m/s

• 1.22 m/s

• 1.25 m/s

Which unit is used to measure distance?

• grams

• seconds

• milliliters

• centimeters

Measuring acceleration requires appropriate units. Which are the SI units for acceleration?

• N

• m/s

• m/s²

• kg*m/s

A car travels in a straight line. The driver applies the brakes and comes to an abrupt stop.

During braking, what happens to the velocity and acceleration vectors?

• They point in opposite directions.

• They point in the same direction.

• They are at right angles to each other.

• They create centripetal acceleration.