Kinesiology 2241A/B Lecture Notes - Lecture 7: Body Force, Parallelogram, Resultant Force

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purpleporcupine895

2 Oct 2016

School

Western University

Department

Kinesiology

Course

Kinesiology 2241A/B

Professor

Thomas Richard Jenkyn

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Document Summary

The physics definition of force is an action that causes mass to be accelerated. It can be a push, pull, run, pressure, blow, impact or gravity. All of these forces add up to a net force. Isaac newton"s 3 laws: objects don"t want to be accelerated because objects possess inertia, the force required to accelerate an object is proportional to its mass (force=mass x acceleration) If a force is applied to an object, the object pushes back with the same force. Things that don"t want to be accelerated. If you are moving at a constant velocity, you to stay still (your acceleration is 0 and you want it to stay 0) If you are going to apply a force to something, it is going to push back on you (action and reaction) There is a force and a reaction but since they are acting on each other movement can occur.

Related Questions

1. Which of the following describes an object with a non-zero netforce acting on it? Choose all that apply.
The moped accelerated while making a left turn.
The motorcycle traveled at a constant speed while making au-turn.
The truck slowed down while making a right turn.
The spaceship traveled at a constant speed in a straightline.
The car sped up from 50 mph to 65 mph while moving in a straightline.

2. If you observe that an object is accelerating, what should youconclude?
A non-zero net force is acting on it. Only forces causeacceleration. As such, if an object is accelerating it must bebecause a non-zero net force is acting on it.
It must be in free fall.
It must be changing direction. Acceleration is a vector and vectorshave both magnitude and direction. Thus if an object isaccelerating it must be changing direction.
The forces acting on the object must be greater than the forces theobject is exerting.
It must be speeding up. If an object is accelerating that means itis speeding up.

3. Which of the following are true according to Newton's 2nd Law?Choose all that apply.

If the acceleration is zero, then the net force is zero.
If you apply the same force to 2 objects, the one with more masswill have a greater acceleration.
If you apply the same force to 2 objects, the one with less masswill have a greater acceleration.
If two objects have the same acceleration, the one with less masswill have a larger net force exerted on it.
If two objects have the same acceleration, the one with more masswill have a larger net force exerted on it.
The larger the net force on an object is, the larger theacceleration.
The larger the net force on an object is, the smaller theacceleration.

4. A box is on the Moon. The box weighs 152 lb and is in free fall.How much force is the box exerting on the Moon and in whatdirection?

lb
Up
Down
Right
North
East
West
Left
South

5. Which of the following are the correct units for mass? Chooseall that apply.
slugs
u
kgÂ·m/s2
g
N
m/s2
oz
lb

6. If an object is traveling in a circle, which of the followingmust be TRUE? Choose all that apply.
The object is slowing down.
The object is speeding up.
The object has a net force acting on it.
The object has a constant velocity.
The object is accelerating.

1. A force is a vector quantity because it has both

A) mass and acceleration.

B) action and reaction counterparts.

C) magnitude and direction.

2. If an object's mass is decreasing while a constant force is applied to the object, the acceleration

A) remains the same.

B) decreases.

C) increases.

3. For an action force, there must be a reaction force that

A) is exactly equal in magnitude.

B) always acts in the same direction.

C) is slightly smaller in magnitude than the action force.

D) is slightly larger in amplitude than the action force.

4. A baseball player bats a ball with a force of 1000 N. The reaction force that the ball exerts against the bat is

A) more than 1000 N.

B) less than 1000 N.

C) 1000 N.

D) impossible to determine.

5. If you push an object a given distance, while applying twice the force, you do

A) twice as much work.

B) four times as much work.

C) half as much work.

D) the same amount of work.

6. A job is done slowly, while an identical job is done quickly. Both jobs require the same amount of work, but different amounts of

A) effort

B) power

C) energy

D) none of these

crimsonbear569

1) An object is moving with constant velocity. Which of the following statements is true?
a) A constant force is being applied in the direction of motion.
b) A constant force is being applied in the direction opposite of motion.
c) There are no forces acting on the object.
d) The net force on the object is zero.
e) There is no frictional force acting on the object.

2) You apply the same force to two objects. Object 1 has mass M and object 2 has mass 5M. The acceleration is
a) ten times that of object 1 b) five times that of object 1
c) the same as that of object 1 d) 1/5 as that of object 1

3) An object of weight W is in free-fall close to the surface of Earth. What is the force that the object exerts on Earth?
a) a force greater than W b) a force less than W
c) a force equal to W d) no force at all

4) A parking crate slides down an inclined ramp at constant velocity. Thus we can deduce that _
a) a frictional force is acting on it
b) a net downward force is acting on it
c) a net upward force is acting on it
d) it is not acted on by appreciable normal force
e) it is not acted on by appreciable gravitational force

5) A person applies a constant force of 20N to a rock of mass 1000kg for a total of 20 seconds. What is the work done by this person if the person does not move at all by this applied force?
a) 1000J b) 2000J c) 20,000J d) 0J e) 400J

6) If the net work done on an object is positive, then the object's kinetic energy.
a) decreases b) remains the same c) increases d) is zero

7) You throw a ball straight up. Compare the sign of the work done by gravity while the ball goes up with the sign of the work done by gravity while it goes down.
a) Work is + on the way up and + on the way down
b) Work is + on the way up and - on the way down
c) Work is - on the way up and + on the way down
d) Work is - on the way up and - on the way down

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Kinesiology 2241A/B Lecture Notes - Lecture 7: Body Force, Parallelogram, Resultant Force

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