Midterm Physics Exam Review

Midterm Physics Exam Review

by Abigail Garcia

SPEED

• Speed is the measure how quickly distance changes with time.

• There are two types of speed: average speed and instantaneous speed.

• Average speed can be found by taking the total distance dividing by total time of travel

• Instantaneous speed is the speed of the object at the specific instant in time.

• Units for speed include mph with SI unit being m/s.

Multiple Choice

Find the speed of Sir Azwan’s car after 40 sec at 8 meters.

• 0.2 m/s

• 5 m/s

• 0.2 mph

• 40 mph

Using Equations to Solve for Speed, Distance, & Time

• Distance = speed x time

• Time = distance / speed

• Speed = distance / time

Multiple Choice

The average speed on 933 is 60mph and it is 30 miles from IISSA to Genting Highland. How long will it take to get to Genting Higland if I leave at 4pm?

• 5min

• 30 min

• 5hrs

• 30 sec

VELOCITY

• Velocity of an object is its speed combined with the direction of the motion

• Just add the direction to the speed and you have velocity

• An example of velocity would be 70m/s south

VECTOR vs SCALAR QUANTITY

• Velocity is a vector quantity while speed is a scalar quantity

• Vector quantity is a physical quantity that has both size and direction

• Scalar quantity is singular, size or direction.

ACCELERATION

• Acceleration is a measure how quickly velocity changes.

• Acceleration describes the change in velocity over time.

• The SI unit for acceleration is m/s^2

Multiple Choice

Shamel is running down the field at first going 15m/s then after 20 sec is going 30m/s. What is his acceleration?

• 0.75 mph

• 2m/s

• 0.75m/s² south

• 2mph

Multiple Choice

It took 3.5 hours for a train to travel the distance between two cities at a velocity of 120 km/hr. How many km lie between the two cities?

• 34 km

• 420 km

• 120 km

• 360 km

Multiple Choice

A roller coasters accelerates from an initial velocity of of 6.0 m/s to a final velocity of 70 m/s over 4 seconds. What's the acceleration?

• 24 m/s²

• 18 m/s²

• 16 m/s²

• 16 m/s

Multiple Choice

A golf ball accelerates off a tee at 15m/s², changing its velocity from 0m/s to 50 m/s down the fairway. How long did it take the golf ball to accelerate?

• 750 s

• 35 s

• 0.3 s

• 3.3 s

Vectors ​

• ​A vector may be represented graphically or algebraically.

• ​Two different displacements are equal when their distances and directions are the same.

• ​Displacement vector is called the resultant vector (the sum of 2 or more vectors).

Magnitude of the Resultant Vector​

​If the two vectors are added at a right angle, the magnitude of the resultant vector can be found using the pythagorean theorem:

​

​

Fill in the Blanks

​Sign of a Component

​​The sign of a component depends on the quadrant of the coordinate system it is in

Multiple Choice

What's the sum of the vectors?

• 50 N -->

• 50 N <--

• 350 N -->

• 350 N <--

Multiple Choice

What's the sum of the vectors

• 13N -->

• 13 N <--

• 113 N -->

• 113 N <--

Multiple Choice

What's the velocity of a bike that travelled -6km in 30 minutes?

• -20

• 20

• -0.20

• 200

Projectile Motion Notes

Projectiles - Objects thrown or launched into the air that are subject to gravity.

Types of Projectiles

• Projectiles launched horizontally

• Projectiles launched at an angle

Components of Projectiles

• Projectiles have two components, just like vectors

• x = horizontal component

• y = vertical component

​Projectile Motion

• ​Projectile motion is a combination of horizontal and vertical motion.

• The combined effect of both motions produces the parabolic path that projectiles follow.

• Each motion, however, is completely independent of each other.

​Projectile Motion

​Projectile motion is the curved motion that results from the combination of an object’s horizontal inertia and the force due to gravity pulling the object downward.

​

​• Examples of projectile motion:

​A ball rolling off a table

A cannon firing a cannonball

A player shooting a jump shot

​

Projectiles follow a parabolic path

​Horizontally Launched Projectiles

​Horizontal motion:

• ​Velocity is constant

• ​Acceleration is zero

​

​Vertical motion:

• ​Velocity is changing

• ​Acceleration is -9.8 m/s²

Equations - Horizontal Motion

Equations - Vertical Motion

Example 1

• Suppose you kick a rock off a 321 m tall bridge. The magnitude of the rock's horizontal displacement is 45 m.

  Find the speed at which the rock was kicked.

Example 2

• Jenny rides her bike off an apartment building in an attempt to land in the pool. The four-story building is 12.5m tall, and she rides at a top speed of 11m/s. 

• How long is she in the air?

• If the pool is 5m from the building, and is 10m wide, will she splash down, land short, or fly right over the pool?

Projectiles Launched at an Angle

​Projectiles Launched at an Angle

• Horizontal Motion:

  • Velocity is constant.

  • Acceleration is zero

• ​Vertical Motion:

  • ​Velocity is changing

  • ​Acceleration is -9.8 m/s^2

Vertical Component

Horizontal Component

Example 1

Example 2

A cannon ball is fired with an initial velocity of 100.0 m/s at an angle of 45° above the horizontal. Find the initial horizontal and vertical components for the initial velocity.

Example 3

Norma kicks a soccer ball with an initial velocity of 10.0 meters per second at an angle of 30.0°.

If the ball moves through the air for 3.2 seconds, what is the horizontal distance traveled by the ball? Round your answer to the nearest tenth.

​

​_____ m

Momentum and Impulse

Formula for Computing for Momentum

Momentum (p) is equal to the mass of the object (kg) multiplied to its velocity (m/s)

Multiple Choice

A biker with a mass of 75 kg moves along the path with a constant velocity of 5 m/s. What is the biker's momentum?

• 25 m/s
• 375 m/s
• 25 kg m/s
• 375 kg m/s

What is impulse?

• It is the external force that acts on an object over a period of time that changes its momentum

• It is measured in Ns or Newton second

• Formula: Impulse (I) is equals to force (N) multiplied with time (s)

​Impulse

Multiple Choice

The units for Impulse are

• kg

• $$N\cdot s$$

• N

• m/s

Multiple Choice

A freight car of mass 20,000kg moves along a track at 15 m/s. What is the momentum of the car?

• 30,000 kg*m/s

• 3,000 kg*m/s

• 300,000 kg*m/s

• 3,000,000 kg*m/s

Multiple Choice

Which takes more force  to catch, a bowling ball or a ping pong ball?

• bowling ball because it has more momentum
• ping pong ball because it has more momentum
• both require the same amount of force when catching
• bowling ball because it has less momentum

Multiple Choice

A 50 kg ball rolls down the street at 5 m/s. Calculate the momentum of the ball. 

• 55 kg*m/s
• 100 kg*m/s
• 250 kg*m/s
• 500 kg*m/s

Multiple Choice

A runner has a momentum of 670 kg m/s and is traveling at a velocity of 9 m/s. What is his mass?

• 74.4 S

• 74.4 N s

• 74.4 kg
• 74.4 N