Transcript Document

Higher Physics Checklist To Date
1. Errors booklet questions 1 - 6 in problem jotter (blue)
2. “Adding Vectors” Tutorial 1 in problem jotter.
(This tutorial can be found in the homework booklet
and a pdf file of the answers is also attached here)
3. Unit 1 Problems 14 - 22 on Adding Vectors, in problem
jotter.
4. HOMEWORK 1 (1995 Past Paper Q1 handout) should be done in RED HW jotter and submitted for
marking.
5. Unit 1 Problems 23 - 26 on Resolving Vectors, in
problem jotter.
6. “Resolving Vectors” Tutorial 2 (Q.1 & 2) in problem
jotter.
(This tutorial can be found in the homework booklet
and a pdf file of the answers is also attached here)
Resolving Vectors (recap)
Components of a Vector
Any single vector can be split into 2 vectors at
right angles to each other.
Eg)
Resolving Vectors
Components of a Vector
Any single vector can be split into 2 vectors at
right angles to each other.
Eg)
Resolving Vectors
Components of a Vector
Any single vector can be split into 2 vectors at
right angles to each other.
Eg)
NOTES p.6
Objects on a Slope
If an object accelerates in some direction, then
the force making it accelerate must be in the
same direction.
For example, a mass (m) on a frictionless slope
which makes an angle, q, with the horizontal …
q
q
W = mg
The force acting on the mass is “gravity” which is
the downwards “weight” of the mass … W = mg.
W = weight in Newtons (N)
m = mass in kg
g = gravitational field strength in N/kg)
q
W = mg
BUT the force affecting the motion of the mass
on the slope is the DOWNSLOPE COMPONENT
OF WEIGHT.
So …
(perpendicular
component)
mg
q
Downslope component
`
of weight = opp = hyp sinq = mg sinq
(perpendicular comp. = mg cosq)
Example
A 2kg mass is released on a slope which makes a
30o angle with the ground. A frictional force of
4N acts upslope. Calculate the acceleration of the
mass.
4N
mg sinq
30o
4N
mg sinq
30o
1st
downslope weight
=
mg sinq
= 2 x 9.8 x sin 30
= 9.8N
2nd
unbalanced force
= FR
= 9.8N – 4N
= 5.8N, downslope
3rd
Fu = 5.8N, downslope
a
= Fu / m
m = 2 kg
= 5.8 / 2
a = ?
= 2.9 m/s2, downslope
So far, the following “Vectors” questions
should be completed
Tutorial 1 (all)
Tutorial 2 (all)
Problems 14 – 22 (addition of vectors)
Problems 23 – 26 (resolving vectors)
+
Homework 1995 Past Paper Q1
Problems 14 – 22 (addition of vectors)
Problems 23 – 26 (resolving vectors)
Tutorial 1 see HW booklet
Tutorial 2 - see HW booklet
Tutorial 1
1.a) 9.9N, 4.95 ms-2
3. a) 4.47ms-1 @ 333o b) 4ms-1 @ 030o
4.a)
b) 20.5ms-1 @ 73o from the horizontal
Tutorial 2
1a) H – 18.8 ms-1, V – 6.8 ms-1
e) H – 0 ms-1, V – 30 ms-1
e) 3.46N
c) H – 17.7 ms-1, V – 17.7 ms-1
2. a) 346N b) 230N c) 11N d) 7.9N
f) 13.8N 3.a)(i) 0.02ms-2 ii) 1.35ms-2 iii) 2.14ms-2
iv) 1.54ms-2 v) 5.05ms-2 b) 19.9o