Page 18 - 1202 Question Bank Physics Form 5

(c) F = ma 1
net (d) W = kʹk 2
30 – 10 – friction = ma 2
1
20 – 10 = 5a = (9 600)(0.15) 2
a = 2 m s 2
–2
= 108 J
(d) F = ma
net
q
2(30) cos – 10 = 0 Section B
2
q = 80.4° 6. (a) • The length of the board should be long so that the component
2 of weight down the board is less. The workers need less force
q = 160.8° to do their work.
(e) (i) Trolley will decelerate • The board should be strong and rigid so that it won’t be
(ii) Trolley will accelerate broken by the heavy load.
(f) Because the component to the right for both 30 N will • The surface of the board should be smooth in order to reduce
q the frictional force resisting the movement of the load.
decrease when angle increases (F cos will decrease when q
increase). 2 • Angle q = 0° so that the rope is parallel to the board to
ensure pulling force needed is minimal.
4. (a)
• The arrangement for Q is chosen because the board is long,
R rigid, smooth and the pulling force is parallel to the board.
(b) Let frictional force = F , F = ma
g net
5 – F = 2(1)
g
mg F = 3 N
g
Apply F = ma again
net
20 – 10 – 3 = 2a
(b) W = mg sin q a = 3.5 m s –2
x
(c) Resultant force
(c) (i)
(d) a = g sin q
Bouyant
a / m s -2 Dragging force, F
force,F V
B
9.8
W = mg
Chapter 1 (e) ©PAN ASIA PUBLICATIONS
(ii) Initially, the weight of the sphere exceeds the buoyant force
and dragging force. The sphere accelerates. However, as
q/°
the velocity of the sphere increases, the dragging force
90°
also increases until finally, the sum of the buoyant force
and dragging force is equal in magnitude to the weight of
u = 0
sphere moves with a uniform downward terminal velocity.
t = 1.2 s the sphere. Then and after, the forces are balanced and the
S h Section C
7. (a) (i) Stiffness is a measure of the resistance offered by an elastic
30 o body to deformation.
(ii) • The thickness of the coil winding for Y is more.
a = g sin q = 9.8 sin 30° • The elongation for Y is less.
= 4.9 m s –2 • The time for 20 oscillations for Y is less, thus the
1
s = ut + at 2 oscillation period of the load is less.
2 • The stiffer the spring the less the swing period.
1
h = 0 + (4.9)(1.2) 2
sin 30° 2 (b) • The spring constant should be high so that it is hard and can
h = 1.8 m support and withstand the weight of the child including a fat
one.
5. (a) Vector: force • The material for the spring and seat should be durable and
Scalar: extention, energy, work, length able to resist wear due to the weather so that it can last longer.
Direction is the one that differentiates vector from scalar. • The diameter of the spring should be large to add stability
(b) (i) Directly proportional and prevent the child from slipping down.
(ii) • The center of gravity of the spring rider is on the axis of the
x / m
spring to add stability while the boy uses it.
(a) • The seat base should be rough so that the child does not slip
while using it.
• The rider’s spring should be mounted on a coarse fabric
0.5
material to prevent injury in case the child falls.
(b)
(c)
F / N
1600
(c) F = kx
1 600 l o
k =
0.5
= 3 200 N m –2
kʹ = 3k x
= 3 µ 3 200
= 9 600 N m –2
134
Answer_1202 Physics F5.indd 134 10/01/2022 12:50 PM