Distance & Displacement
What term describes the total path traveled by an object?
distance
A car travels 100 m in 20 s. What is its average speed?
5 m/s
What is a push or pull on an object called?
Force
What force opposes motion between surfaces that are touching?
Friction
An object at rest stays at rest unless acted on by an unbalanced force. Which Newton's Law describes this?
Newton's First Law
What two quantities determine an object's momentum?
Mass and velocity
What force pulls objects toward the center of Earth?
Gravity
A student walks 12 m from the classroom to the water fountain. How much distance did the student travel?
12 m
A runner moves at 6 m/s west. Is this speed or velocity? Why?
Velocity because magnitude and direction are given.
Two students push a box in opposite directions with 25 N each. What is the net force?
0 N
A heavy box is sitting on the floor. You push on it, but it does not move. What type of friction is preventing it from starting to move?
Static friction
What is the name for an object's tendency to resist a change in its motion?
Inertia
What equation is used to calculate momentum?
p = mv
An astronaut travels somewhere with weaker gravity. Which changes: the astronaut's mass or weight?
Weight changes; mass stays the same.
A student walks 10 m east and then 4 m west. Find the distance and displacement.
Distance = 14 m; Displacement = 6 m east
A cyclist travels 150 m at an average speed of 5 m/s. How long did it take to complete this trip?
30 s
A box has a 40 N force right and a 10 N force left. Find the net force and direction.
30 N right
Identify the type of friction in each situation: (A) a sled moving across snow, (B) a bicycle tire moving along the road, (C) a swimmer moving through water.
A = Sliding friction; B = Rolling friction; C = Fluid friction
A passenger moves forward when a car suddenly stops. Which Newton's Law explains this?
Newton's First Law
A 3 kg ball moves at 4 m/s. Calculate its momentum.
12 kg·m/s
What is the acceleration due to gravity near Earth's surface?
About 9.8 m/s² downward
A student walks 15 m north and then walks 15 m south back to the starting point. Find the distance and displacement.
Distance = 30 m; Displacement = 0 m
A bicycle's velocity changes from 4 m/s to 16 m/s in 4 seconds. Calculate its acceleration.
3 m/s²
A book rests motionless on a table. Are the forces acting on the book balanced or unbalanced? How do you know?
Balanced; its motion is not changing.
A box is sliding to the right across the floor. In what direction does the force of friction act? Explain.
To the left. Friction acts opposite the direction of motion.
A 6 kg cart accelerates at 3 m/s². Calculate the net force acting on the cart.
18 N
Object A has a mass of 2 kg and moves at 8 m/s. Object B has a mass of 4 kg and moves at 4 m/s. Which has more momentum?
They have equal momentum: 16 kg·m/s each.
A 6 kg object is on Earth. Using g = 9.8 N/kg, calculate its weight.
58.8 N
A student walks 8 m east and then 6 m north. What is the the student's displacement?
10 m NE
A car travels around a curve at a constant speed of 20 m/s. Is the car accelerating? Explain.
Yes. Its direction changes, so its velocity changes.
A box moves to the right but begins slowing down. What does this tell you about the direction of the net force?
The net force is to the left, opposite the box's motion.
A student pushes a box with 50 N to the right. Friction acts with 20 N to the left. Calculate the net force and predict what will happen to the box's motion.
30 N right. The forces are unbalanced, so the box accelerates to the right.
A balloon releases air backward and moves forward. Identify the action and reaction and the Newton's Law involved.
Action: balloon pushes air backward. Reaction: air pushes balloon forward. Newton's Third Law.
A 5 kg cart increases its velocity from 2 m/s to 6 m/s. Calculate its momentum before and after.
Before = 10 kg·m/s; After = 30 kg·m/s
A falling object reaches a point where gravity downward equals air resistance upward. What has the object reached, and what happens to its velocity?
Terminal velocity; it continues falling at a constant velocity.
A student walks 12 m east, 5 m west, 9 m east, and then 4 m west. Calculate the total distance and final displacement.
Distance = 30 m; Displacement = 12 m east
A car changes velocity from 28 m/s to 8 m/s in 5 seconds. Calculate its acceleration and explain what the answer tells you about its motion.
−4 m/s². Its velocity is decreasing
A student pushes a box right with 65 N. Friction acts left. The box has a net force of 20 N right. Calculate the frictional force.
45 N left
Two identical boxes are pushed with the same applied force. Box A moves across a smooth tile floor. Box B moves across rough carpet and accelerates less. Use friction and net force to explain why Box B has less acceleration.
The rough carpet produces more friction opposing Box B's motion. This reduces its net force. With the same mass but a smaller net force, Box B has less acceleration.
Two carts each experience a 24 N net force. Cart A has a mass of 3 kg and Cart B has a mass of 8 kg. Calculate the acceleration of each and explain why they are different.
A = 8 m/s²; B = 3 m/s². With the same force, greater mass produces less acceleration.
Object A has a mass of 10 kg and moves at 3 m/s. Object B has a mass of 5 kg. How fast must Object B move to have the same momentum as Object A?
6 m/s
A ball is thrown forward. Explain why its path curves downward and what happens to its downward velocity as it falls.
Forward motion carries it forward while gravity accelerates it downward. Its downward velocity increases as it falls, producing a curved path.