Kinematics

Question 1

Frame of reference

Answer 1

a chosen body we use to correlate the motion of other bodies with.

Question 2

Coordinate system

Answer 2

used to describe motion of bodies quantitatively

Question 3

A rigid body

Answer 3

a solid body which retains it’s shape and it’s motion can be described by the combination of translation and rotation

Question 4

What is translation and how does the velocity change during displacement?

Answer 4

A body is displaced along a set of parallel straight lines from one position to another, the orientation of the body in space is unaltered.

The velocity of all the points of the body has the same magnitude and direction.

Question 5

Rotational movement

Answer 5

All the points of the body move along concentric circular paths around a center point of rotation (pivot)

Question 6

Velocity

Answer 6

v= Δs/Δt

the instantaneous velocity of an object is calculated from the smallest Δt possible.

unit: m/s

a vector quantity

Question 7

Speed

Answer 7

the scalar absolute value of velocity

Question 8

Linear motion with uniform velocity

Answer 8

The velocity is constant and the distance traveled will be directly proportional to time. The s vs t graph is linear.

Question 9

Acceleration

Answer 9

change of velocity over elapsed time - rate of change of velocity of an object
increasing velocity = +
decreasing velocity= -

unit: m/s^2

Δt needs to be small enough so that the change in acceleration is negligible.

a vector quantity

Question 10

Linear motion with uniform acceleration

Answer 10

v= a*t+v(initial)

constant acceleration

Question 11

Linear motion with uniform velocity

Answer 11

s = v*t

constant velocity

Question 12

Average velocity

Answer 12

used for distance traveled during a time interval (linear motion with uniform acceleration

v(average)=(v1+v2)

Question 13

Gravitational acceleration (g)

Answer 13

constant acceleration of a free-falling object caused by force of gravitation
mean value: 9,81 m/s^2
rock falling: v is increasing by g every second
rock thrown up: v is decreased by g every second

Question 14

Angular motion

Answer 14

the angular displacement divided by time elapsed. angles should always be written as RAD, because the unit is 1/s and it actually means rad/1.

a vector value.

Question 15

Uniform circular motion

Answer 15

constant angular velocity.

φ = ω * t

Question 16

Velocity of uniform circular motion

Answer 16

v=r* ω

Question 17

Period

Answer 17

symbol (T)
unit: s
duration of one cycle in a repeating event
time of one revolution

Question 18

Frequency

Answer 18

number of occurrences of a repeating event per unit time
f=1/T

symbol: f unit: 1/s

Question 19

Rotation

Answer 19

the points of a rotating rigid body moving along a circular path with an axis of rotation.

Question 20

(PP) A pilot of 90 kg catapults horizontally at a height of 4000 m from an airplane. What is his altitude 15 s after hitting the catapult button, if suppose he falls freely?
A) 3925 m
B) 2875 m
C) 1125 m
D) 75 m

Answer 20

C ??

Question 21

(PP) A train traveling at 31 km/h accelerates uniformly to 85 km/h in half a minute. Calculate it's acceleration.
A) 54 m/s^2
B) 0,5 m/s^2
C) 0,14 m/s^2
D) 15 m/s^2

Answer 21

B) ??

Question 22

(PP) An object of 0,5 kg falls from a height of 5 meters. What is its velocity when reaching the ground?
A) 1 m/s
B) 10 m/s
C) 50 m/s
D) 100 m/s

Answer 22

??