Vectors and Balanced Force Model

Question 1

If the force of gravity suddenly stopped acting on the planets, they would

Accepted Answer

Move in straight lines tangent to their orbits

Question 2

A velocity is (18, -4) m/s. What vector means twice the speed in the opposite direction?

Accepted Answer

(-36, 8) m/s

Question 3

Friction is a force that acts

Accepted Answer

opposite to the direction of motion

Question 4

Newton’s 1st Law states that an object at rest remains at rest unless a force is applied to it.

Accepted Answer

False

Question 5

Which types of forces will cause a change in an object’s motion?

Accepted Answer

unbalanced forces

Question 6

A force always requires contact between two objects

Accepted Answer

False

Question 7

A 2-kg object moves at 4 m/s. What force needed to keep it at same speed in same direction?

Accepted Answer

0 N

Question 8

Jane travels 8 km east and 2.5 km south. Express vector in polar notation.

Accepted Answer

(8.38 km, 342.65 degrees)

Question 9

An object moving at a constant speed in a straight line

Accepted Answer

Has zero acceleration

Question 10

What is mass?

Accepted Answer

Tendency of an object to resist a change in its motion

Question 11

Drifting astronaut might be able move opposite direction by throwing tool in the dir of travel.

Accepted Answer

True

Question 12

J hikes 8 km 28 deg east of North. What vector is the same distance in the opposite direction?

Accepted Answer

(8 km, 242 degrees)

Question 13

Initial velocity (380, 240) m/s. After 2 minutes, velocity (286, -60) m/s. Displacement?

Accepted Answer

(39960, 10800) m

Question 14

Plane accelerates at 11 m/s/s in direction 31 degrees south of west. Express polar notation.

Accepted Answer

(11 m/s/s, 211 degrees)

Question 15

You push a cart. By N's 3rd Law, cart pulls you with equal & opposite force. Why can cart move?

Accepted Answer

Less frictional force on cart wheels than on your shoes.

Question 16

A plane goes 258 m/s 22 deg west of north. Express velocity as rectangular notation vector.

Accepted Answer

(-96.65, 239.21) m/s

Question 17

An object moving at a constant speed in a straight line

Accepted Answer

Will move forever as long as zero net force acts on it

Question 18

An object speeding up in straight line must have net force acting in the direction of motion.

Accepted Answer

True

Question 19

An object with zero net force could be moving in a circle at a constant speed

Accepted Answer

False

Question 20

The normal force always points in the opposite direction of the gravitational force.

Accepted Answer

False

Question 21

Gravity force pulls down. Floor pushes up w same force opposite dir. These are 3rd Law Pairs.

Accepted Answer

False

Question 22

A rover weighs 1000 N on earth. What is weight on Mars where g is 4.28 N/kg?

Accepted Answer

437 N

Questions 22