Physics answers now posted ~ RUMADES

: 8ai)
Force is a push or pull which changes a body state of rest or of uniform motion in a straight line
8aii)
The two types of force are
*constant force
*field force
*magnetic force
*gravitational force
=====
5)
i)availability of constant sunlight
ii)nearness to power grid
iii)must be closer to both skilled and unskilled labour
[10:06AM, 9/14/2017] Waka Gist Admin: *Question one*
(a) Horizontal speed just before it strikes floor = ucos(theta)
= 10cos0°
= 10 m/s

(b) t = √(2g/h)
        = √(2*10*1)
        = √20
        = 4.47s

Question 4
(a) given: u = 20m/s
                   t = 4s
                   g = 10m/s²
                   h = ?
    Using s = ut - ½gt²
               s = 20(4) - ½(10)(4)²
               s = 0m

(b) The inference is that after 4s, the ball returns back to the plane of projection

Question 3
Magnetic materials: ¶ Iron ¶ Cobalt ¶ Nickel

Question 2
¶ medical uses
¶ welding and cutting
¶ military uses for defense and counter measures

Question 5
The factors that determine the location of a solar power station are
¶ Intensity of sun light
¶ surface slope
¶ feeder capacity of the distribution center

Question 11
(a) ¶ Electrical method
¶ Contact method

(b) Electric lines of force are imaginary lines drawn in an electric field in such a way that the direction at any point gives the direction of the electric field at such a point

(d) Resistivity is the resistance of a unit length of material of unit cross-sectional area

(e) Given: F = 50Hz
                   L = 10 mH (10×10^-³H)
       Inductive reactance, XL = 2πFL
                                                  = 2×3.14×50×10×10^-³
                                                  = 3..14 ohms

(f) If voltmeter reads 12V, over the 500 ohms, then using I = V/R
                                                            current in the circuit is I = 12/500
                                                                                                     I = 0.024A
     Hence over the 200 ohms, V = IR
                                                    V = 0.024×200
                                                    V = 4.8 VOLTS
     Voltmeter will read 4.8 volts

*Question 9*
(a) Poor conductors of heat application: ¶ Coat (Trapped air in between the fabric)
¶ The hair and the fur of animals are bad conductors of
heat and they protect them from cold .

(b) Renewable: Water, corn stalk
Non-renewable: coal, natural gasgas

d) heat required to melt = mc∆ + ml
*NB*: Not sure of the temperature given, if it is -3°C or -5°C, However, *Using -3°C*
Heat = (0.1×2200×3)+(0.1×2.26×10^6)
= 226660 J

e) (i) Given: 75 heart beats in 1 min
                      Therefore in 1 hour, we have (75×60) heart beats = 4500 heart beats
         Also given: 2J of energy is expended in 1 heart beat
                       Therefore for 4500 heart beats, energy expended = (4500×2) J = 9000J

e) (ii) Energy = mc∆
           9000 = (0.25×4200×∆)
           9000 = 1050∆
           ∆ = 9000/1050
           Temperature rise = 8.57°C

Question 8

a)(i) A force is anything that causes motion
(ii) ¶ contact force
¶ field force

b)(i) Bodies are streamlined so they can overcome to a great extent the viscosity that exists in fluids
(ii) ¶ submarines
¶ seals

8c
i) ¶ Fg is downwards
¶ T1 is upwards

ii) ¶ a = v²/r
a = 7²/1.2
a = 40.8 m/s²

    ¶ F = ma
          = 1.3 × 40.8
          = 53N: SECTION-A ANS 5 ONLY
================================
4a)
Time (t)=4secs
V=0ms^-1
pie call,V^2=U^2+2gh
O^2=20^2+2(-10)h
0=400-20h
20h/20=400/20
h=20m
4b)
the magnitude of the initial speed (u) is equal to the magnitude of the height attained
================================

================================
2)
i)used ineye surgery
ii)used for the precise cutting of flat material
iii)used for measuring distances
================================
3)
i)iron
ii)steel
iii)nickel
================================
5)
i)availability of constant sunlight
ii)nearness to power grid
iii)must be closer to both skilled and unskilled labour
================================
Keep Refreshing
Typing/Solving
: (6)
P-type semi conductors are created by dopung an intrisic semi conductor with acceptor impurities.
================
: 1.
(a) Horizontal speed just before it strikes floor = ucos(theta)
= 10cos0°
= 10 m/s

(b) t = √(2g/h)
= √(2*10*1)
= √20
= 4.47s
=============================

2
- medical uses
- welding and cutting
- military uses for defense and counter measures
================================

3.
Magnetic materials:
- Iron
- Cobalt
- Nickel
===============================

4.
(a) given: u = 20m/s
t = 4s
g = 10m/s²
h = ?
Using s = ut - ½gt²
s = 20(4) - ½(10)(4)²
s = 0m

(b) The inference is that after 4s, the ball returns back to the plane of projection
===============================

5.
The factors that determine the location of a solar power station are
- Intensity of sun light
- surface slope
- feeder capacity of the distribution center
===============================

8a)
i. Force is a push or pull which changes a body's state of rest or uniform motion in a straight line.

ii.
a) field force
b) contact force

8b)
i. Bodies streamlined in
Shape move through fluid so as to oppose or overcome the motion of the fluid

ii.
a) fish
b) submarine

8c)
Mass= 1.3 kg
F= 1.2 m
V= 7.0 m/s

Drawing

ii. Acceleration
Note , V²= U² + 2as

Where S=r=1.2 m

(7.0)²= 0²+2× a (1.2)

= 49/2.4 = 2.4a/2.4

a = 20.4

B) Force=?
From force = MA
Force =1.3×20.4
Force =25.52
===============================

9)
(a) Poor conductors of heat application: - Coat (Trapped air in between the fabric)
- The hair and the fur of animals are bad conductors for heat and they protect them from cold .

(b)
Renewable: Water, corn stalk
Non-renewable: coal, natural gas

d) heat required to melt = mc∆ + ml
Note: Not sure of the temperature given, if it is -3°C or -5°C, However,
Using -3°C
Heat = (0.1×2200×3)+(0.1×2.26×10^6)
= 226660 J

e)
i. Given: 75 heart beats in 1 min
Therefore in 1 hour, we have (75×60) heart beats = 4500 heart beats
Also given: 2J of energy is expended in 1 heart beat
Therefore for 4500 heart beats, energy expended = (4500×2) J = 9000J

ii. Energy = mc∆
9000 = (0.25×4200×∆)
9000 = 1050∆
∆ = 9000/1050
Temperature rise = 8.57°C
================================
11)

(a)

- Electrical method
- Contact method

(b) Electric lines of force are imaginary lines drawn in an electric field in such a way that the direction at any point gives the direction of the electric field at such a point

(d) Resistivity is the resistance of a unit length of material of unit cross-sectional area

d) heat required to melt = mc∆ + ml
Note: Not sure of the temperature given, if it is -3°C or -5°C, However, *Using -3°C*
Heat = (0.1×2200×3)+(0.1×2.26×10^6)
= 226660 J

(e) Given: F = 50Hz
L = 10 mH (10×10^-³H)
Inductive reactance, XL = 2πFL
= 2×3.14×50×10×10^-³
= 3..14 ohms

RUMADES

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Thursday 14 September 2017