Physics Review- Newton's Laws of Motion

A 2 kg object is dropped from rest and free falls. After 4 seconds, what is the speed/distance?

40 m/s and 80 M

Determine acceleration of object with a net force of 25 (Use 10 m/s/s for g)

5 m/s/s

An object has an acceleration of 8 m/s/s. If the net force decreased by a factor of 3.7 and mass decreased by 2.6, the new acceleration is....

5.6 m/s/s

An object weighs 530 newtons. It is being pushed along a horizontal path surface by 340 newton force. Determine Mass

54 Kg 530=9.8m

The force of Gravity of object on the moon is 1.6 m/s/s. Joe weights 600 N on Earth. What is the mass on the moon?

60 Kg 600=9.8m m=60; Mass will stay the same!

An object is moving right at a constant velocity of 2 m/s. What is the horizontal force required to maintain this state of motion?

0 N

acceleration of gravity on Earth

9.8 m/s/s

Determine mass of an object that experiences an acceleration of 5 m/s/s and a net force of 493 N.

98.6 Kg

If you were in a spaceship and launched a cannonball into frictionless space, how much force would have to be exerted on the ball to keep it going?

Zero; since there is no force necessary to keep the object moving (Inertia)

Weight

A measure of the force of gravity on an object

Rank each object in order of acceleration (Small to Large) with a mass of 5 kg. A. Net Force of 0 b. Net Force of 20 c.Net Force of 15 d. Net Force of 25

ACBD

Which of the following are true for free-falling objects? a. Grav. is the only force b. velocity of the object is continuously changing c. Accel.of Object is 9.8 m/s/s d. Fnet=Mg e. Such objects accelerate at a rate dependent upon the mass f. Air Resist. has a negligible effect upon object g. None

ACDF

A skydiver pulls the chord on his parachute. Forces are acted upon the diver and shown below. One might infer the skydiver will accelerate _________ and the divers will ____________ 2000N (Fair) ☐ 1000N (Fg)

Accelerate Upwards/Slow Down

When an object reaches terminal velocity it has stopped..

Accelerating

The forces acting upon an object are NOT BALANCED. The object is .....

Accelerating/Changing Velocity

What can you conclude from the diagram? (Accel/Speed) 2000 N ☐ 1000 N

Acceleration is Up and Continues to fall but will slow down

The value of g is 9.8 m/s/s. 'g' stands for

Acceleration of Gravity

The air resistance of a falling object would decrease if..

Air Density/Cross-Sectional Area of Object/Speed of Falling object decreases

Which of the following are true for free-falling objects of different masses? a. Experience the same force of gravity b. rate of acceleration. is the same c. same acceleration but different g value d. Same g value and different acceleration e. None

B

Spring Force

The spring force is the force exerted by a compressed or stretched spring upon any object that is attached to it.

a 6 kg object is moving right w/ a constant velocity of 4 m/s. What is the net force?

0 N

A 2 kg object is thrown upwards w/initial velocity of 10 m/s. At the peak, what is the acceleration and Net Force?

10 m/s/s and 20 N

Determine Weight of a 1768 Kg object going at 20 m/s.

17326 N

Are these unbalanced or balanced? . . . . . .

Unbalanced

A 3 kg object is dropped from rest and free falls. After 2 seconds, what is the speed/distance?

20 M/s and 20 M

An object has an acceleration of 14.1 m/s/s. If the mass decreased by a factor of 1.6, the new acceleration would be...

22.6 m/s/s

An object has an acceleration of 7.6 m/s/s. If the Fnet increased by a factor of 3.5, the new acceleration would be...

26.6 m/s/s

Determine acceleration of a 6 kg object with a Fnet of 21 N

3.5 M/s/S

Which of the following statements are true? a. the mass of an object is the Fg acting upon object b. The weight of object on the moon will be same as on the earth c. the mass of an object on the moon will be same as on the earth d. On Earth, more massive objects weigh more than less massive ones. e. The mass and weight of an object are the same thing. f. the weight is its mass multiplied by the Fg.

CD

Suppose that an astronaut throws a rock into space. One would expect that the rock would...

Continue in motion with the same speed/direction

Label the Objects by inertia from greatest to least a). 5 kg (a=1 m/s/s) b). 4 kg (a=3 m/s/s) c). 3 kg (a=2 m/s/s) d). 10 kg (a=0 m/s/s)

DABC

Which of the following would have the effect of decreasing the acceleration?

Doubling the Mass and decreasing the net force

A <- moving object is changing speed. The net force of the object must be directed _______

East/Westward

T/F: If an upward moving object experiences an unbalanced force, then the object will have an acceleration which is up.

FALSE

A 70 kg Skydiver encounters 490 N air resistance force. Determine Fair, Fg, Mass, Fnet, and acceleration

Fair = 490 N, Fgrav = 700 N, Mass = 70 Kg, Fnet = 210 N, a = 3 m/s/s

T/F: An object is in free-fall if it is falling and no one is pushing it and there is no strings attached

False

When an object reached terminal velocity...

Fg and Fair is equal, Acceleration is 0 m/s/s, velocity is at a constant value, and net force is 0 N

Formula for Weight (Fg)

Fg=mg

terminal speed

Final Speed to which an accelerating object can accelerate

Identify Forces Involved Book sliding across table (Ignore A.R)

Friction Normal Gravity

Identify Forces Involved Large crate being pushed across the floor w/constant velocity (Ignore A.R)

Friction Normal Gravity Applied

Identify Forces Involved Moving Truck skids to a stop from very high speed w/wheels locked

Gravity Friction Normal Air Resist

Identify Forces Involved Person standing upon the ground

Gravity Normal

Identify Forces Involved Elevator is suspended by cables/descends through the shaft (No Contact w/Wall and Ignore A.R)

Gravity Tension

Identify Forces Involved A dog being pulled by a chain across ground at constant speed (Ignore A.R)

Gravity Tension Friction Normal

A diver steps off a plane. As the skydiver falls her speed increases. This causes A.R force to -______ and acceleration to ______

Increase/Decrease

Jack and Jill argues. Jack says that if he flings jello with a greater speed, it will have a greater inertia. Jill argues that interim does not depend on speed, but on mass. Who is right?

Jill; Inertia solely depends on mass

When all individual forces acting on an object are balanced, it is the natural tendency of an object to .....

Keep its constant velocity AND maintain its state of motion

Mass is expressed in units of _______ and weight in units of _________

Kg, N

Is Inertia a force?

NO

A 50 N force is applied to a 25 Kg object to accelerate rightward. Object encounters a 20 N friction force. Determine Fnorm, Fapp, Fgrav, Ffrict, Fnet, mass, and acceleration

Norm= 250 N, App= 50 N, Grav= 250 N, Frict=20 N, Net= 30 N, M=25 Kg, a= 1.2 m/s/s

A Leftward moving object is coasting to a stop. The net force must be directed

Rightward

Newton's 2nd Law of Motion

The acceleration of an object as produced by a net force is directly proportional to the magnitude of the net force, in the same direction as the net force, and inversely proportional to the mass of the object.

Tension Force

The force that is transmitted through a string, rope, cable or wire when it is pulled tight by forces acting from opposite ends

Do all objects have inertia?

Yes

What is the law of inertia?

a body in motion will remain in motion unless acted on by an unbalanced force / a body at rest will remain at rest unless acted on by an unbalanced force

Applied Force

a force which is applied to an object by a person or another object

Air Resistance Force

a special type of frictional force that acts upon objects as they travel through the air.

Newton's 2nd Law Formula

a=Net Force/mass

An object moving with constant velocity MUST

be experiencing a balance of forces

The law of inertia applies to ...

both moving and nonmoving objects

When all individual forces acting on an object are balanced, it is the natural tendency of an object to ...

maintain state of motion/keep their velocity constant

The forces acting upon an object are BALANCED. The object is ....

not accelerating

Inertia

property of an object that describes its natural tendency to keep on doing whatever it is doing

acceleration of gravity

the acceleration of a falling object

Mass

the amount of matter in an object

A ball is thrown upwards vertically. After the ball is released and is moving upwards towards its peak, it slows. During this time, the ball is experiencing an _________ force and is directed _________.

the ball is experiencing an unbalanced force; directed downward

Friction Force

the force exerted by a surface as an object moves across it or makes an effort to move across it

Gravity Force

the force with which the earth, moon, or other massive body attracts an object towards itself

free fall

the motion of a falling object when the only force acting on it is gravity

A sled slides down a hill and reaches the surface and soon stops. The fact that the sled ultimately stops is best explained by ...

the presence of an unbalanced force can cause a moving object to stop

A massive and less massive object free-fall at the same rate because ....

the ratio of the Fnet to mass is the same for each

normal force

the support force exerted upon an object that is in contact with another stable object

Inertia refers to

the tendency of moving objects to remain in motion OR the tendency of stationary objects to remain at rest

Suppose that an elephant and feather are dropped. In the presence of A.R, the elephant would fall faster because...

the weight of the elephant is much greater; A.R effects it less