Mechanics

Question 1

State the suvat equations

Answer 1

• s = (u + v)t / 2
• a = v - u / t
• s = ut + 1/2at²
• v² = u² + 2as

Question 2

What is the difference between distance and displacement?

Answer 2

• Displacement is a vector
• Distance is scalar

Question 3

What does a horizontal line represent on a displacement time graph?

Answer 3

• Stationary

Question 4

What does a straight line where gradient is not zero mean on a displacement time graph?

Answer 4

• Constant speed

Question 5

How is constant velocity forwards and backwards represented on displacement time graph?

Answer 5

• Constant velocity forwards is a straight line angled up
• Constant velocity backwards is a straight line angled down

Question 6

How do you represent a stationary object on a velocity time graph?

Answer 6

• Horizontal line at zero

Question 7

How do you represent a constant speed on a velocity time graph?

Answer 7

• Horizontal line

Question 8

How do you represent a constant accleration on a velocity time graph?

Answer 8

• Straight line angled up

Question 9

How do you represent a constant decelleration on a velocity time graph?

Answer 9

• Straight line angled down

Question 10

What does gradient represent on a velocity time graph?

Answer 10

• Acceleration

Question 11

How do you represent a stationary object on an acceleration time graph?

Answer 11

• Can’t be shown

Question 12

How do you represent constant speed on an acceleration time graph?

Answer 12

• Horizontal line at zero

Question 13

What represents a changing acceleration on an acceleration time graph?

Answer 13

• A straight line angled up or down

Question 14

What does the gradient represent on an acceleration time graph?

Answer 14

• Jerk

Question 15

Describe what a displacment, velocity and acceleration time graph would look like if a ball was thrown straight up into the air and then fell back down.

Answer 15

Question 16

How do you find percentage error of multiple readings?

Answer 16

1. Find range
2. Range / 2 = Uncertainty
3. %d = Uncertainty / Average value

Question 17

How do you find percentage error of a single reading?

Answer 17

1. Uncertainty = Resolution of instrument / Reading
2. Then divide by 2

Question 18

What is a vector quantity?

Answer 18

• Vector quantities have magnitude and direction

Question 19

What is a scalar quantity?

Answer 19

• Has magnitude only

Question 20

What is Newtons 1st law?

Answer 20

• States that a body will remain at rest or move with uniform velocity unless acted upon by a resultant external force

Question 21

What Newtons 2nd law?

Answer 21

• States for a body of fixed mass, acceleration is directly proportional to the resultant force applied to the body
• F = ma
• Δp / t = F

Question 22

What is Newtons 3rd law?

Answer 22

• States if object A exerts a force on object B then object B exerts an equal and opposite force on object A

Question 23

What is the equation for gravitational field strength?

Answer 23

• g = F / m

Question 24

What is the equation for weight?

Answer 24

• W = mg

Question 25

What is the equation for momentum?

Answer 25

* p = mv

Question 26

What is the conservation of momentum?

Answer 26

* Total momentum before = Total momentum after if no resultant external force acts

Question 27

What is the moments equation?

Answer 27

* Moment = Fd * Moment = Force \* Perpendicular distance from pivot

Question 28

What is the principle of moments?

Answer 28

* In equilibrium, total moments clockwise = total moments anticlockwise

Question 29

What is the centre of gravity?

Answer 29

* The point at which all weight acts

Question 30

What is the equation for impulse?

Answer 30

* Δp = Ft

Question 31

What is the equation for kinetic energy?

Answer 31

* KE = 1/2mv²

Question 32

What is the equation for GPE?

Answer 32

* GPE = mgh

Question 33

What is the principle of concervation of energy?

Answer 33

* Energy cannot be created or destroyed only transfered from one form to another

Question 34

What is the equation combining GPE and KE?

Answer 34

* 1/2mv² = mgh

Question 35

What are the equations for power?

Answer 35

* P = E/t * P = W/t * Energy transfered = Work done * P = I²R * P = V²/R

Question 36

What are the equations for effeciency?

Answer 36

* Efficiency = Useful energy output / Total energy input * Efficiency = Useful power output / Total power input

Question 37

What should you do when dealing with projectiles?

Answer 37

* Treat horizontal and vertical motion separatly using suvat

Question 38

What is the equation for work?

Answer 38

Work done = Force in direction of travel × Distance

Question 39

What is a Newtons Third law pair of forces?

Answer 39

* Same type of force * Same size * Opposite direction * Act of different bodies * Same line of action * Act for same time

Question 40

Equation for velocity

Answer 40

* Velocity = displacement / time

Question 41

If you get stuck think...

Answer 41

ENERGY, UNITS, RESULTANT FORCES, ACCELERATION

Question 42

Core practical 1: acceleration of free falling object * Independant variable * Dependant * Equation * y=mx + c * Graph to plot * Equipment = Light gate and data logger

Answer 42

* Height dropped * Final Velocity * v² = u² + 2as * y=mx + c * y axis plot v² * x axis plot s

Question 43

What is the power equation that includes force?

Answer 43

* P=fv

Question 44

What is change in momentum for one object?

Answer 44

* Change in momentum = final momentum - initial momentum

Question 45

What must you remember whilst drawing a force free body diagram?

Answer 45

* CUT IT OUT OF THE PICTURE * Only forces acting on the body

Question 46

How do you calculate displacment for object traveling in curve or circle?

Answer 46

* Draw a straight line from start to finish and use pythag