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Published by fika 16, 2020-07-13 22:18:21

QUESTION_TUTORIAL4_SDS

QUESTION_TUTORIAL4_SDS

LECTURE/ TUTORIAL/ PRACTICAL CHECKLIST

CHAPTER: 4 (FORCES)

SUBTOPIC/LEARNING OUTCOME LECTURE TUTORIAL PRACTICAL
4.1 Basics of forces and free body diagram /

a. Identify the forces acting on a body in
different situations:
i. Weight
ii. Tension
iii. Normal Force
iv. Friction
v. External Force (pull or push)

b. Sketch free body diagram. / /
/ /
c. Determine static and kinetic friction.
fs  sN /
fk = k N

4.2 Newton’s Law of Motion
a. State Newton’s Law of motion

b. Apply Newton’s law of motion

C2, PLO1, MQF LOD 1

1. Which of the following statements describes what must be true in the context of
Newton’s First Law?
A. The object is difficult to bring a complete stop due to its high initial speed.
B. The tendency for drivers to keep moving linearly while the car makes a sharp turn
on the road is an example of the concept of inertia.
C. Mass is a measure of an object’s ability to resist motion or movement of any kind.
D. An object with zero acceleration and an object traveling at a constant acceleration
are considered similar states.

C1, PLO1, MQF LOD 1
2. Which statement below is Newton's Third Law of Motion?
A. If an object is acted upon by an external, unbalanced force the object will accelerate
in the direction of the net force.
B. An object will remain at rest or in uniform motion in a straight line unless acted upon
by an external, unbalanced force.
C. For every action force there is an equal and opposite reaction force.
D. The natural tendency of an object to remain in a state of rest or in uniform motion in a
straight line

C2, PLO1, MQF LOD 1

3. Which of Newton's Laws is demonstrated by a ball strikes to a wall then rebound?
A. Newton's First Law
B. Newton's Third Law
C. Newton's Second Law
D. Newton's Law of Acceleration

C2, PLO1, MQF LOD 1
C4, PLO4, MQF LOD 6

4. a) Differentiate between static friction and kinetic friction.

b) Ali wants to move a 50 kg crate across a level floor. To start crate moving, Ali has to
pull with 230 N horizontal force. Once the crate starts to move, Ali can keep it
moving at constant velocity with only 200 N. What are the coefficients of static and
kinetic friction?
[0.47, 0.41]

C1, PLO1, MQF LOD 1
C4, PLO4, MQF LOD 6

5. a) State Newton’s 1st Law.
b) Use newton’s First Law of Motion to explain why passengers standing in a bus are
thrown
(i) backwards when the bus starts to move.
(ii) forward when the bus stops suddenly.

C1, PLO1, MQF LOD 1
C4, PLO4, MQF LOD 6

6. a) State the Newton’s Law that relates to concept of inertia.
b) Three horizontal forces F1, F2, and F3 act on an object as shown in diagram below.
F2 = 4.0 N

F1 = 6.0 N F3 = 2.0 N

Find the direction and magnitude of the fourth force to keep the object in equilibrium.
[5.66 N, 45° below positive x-axis]

C4, PLO4, MQF LOD 6

7. Faaiz cycling around the college at a speed of 10.5 ms-1. Arriving in front of block A1,
as he climbs into the Dewan Besar the speed of his bike decreases to 8.8 ms-1 in 14
seconds. If the total mass of Faaiz and his bicycle is 70 kg.

a) Determine the decelerations experienced by him.
b) Determine the force of friction experienced by the bike tire.
c) Determine the coefficient of friction between the road and the bike tire.

[0.12 ms-2, 8.4 N, 0.012]

C4, PLO4, MQF LOD 6

8. a) A rope is used to pull a 2.89 kg bucket of water out of a deep well.
i) What is the acceleration of the bucket when the tension in the rope is 30.2 N ?
ii) If starting from rest, what speed will the bucket have after experiencing this force
for 2.16 seconds
[0.64 ms-2, 1.38 ms-1]

b) A crate of mass 100 kg is pulled along a rough surface by two ropes at the angles
shown.

120 N

100 kg 20o
20o

120 N

(i) If the crate is moving at a constant speed of 1 ms-1, what is the frictional force?
(ii) If the forces were increased to 140 N at the same angle, calculate the acceleration

of the crate.
[225.5 N, 0.376 ms-2]

C4, PLO4, MQF LOD 6

9. a) A block of mass 6 kg on a smooth table is connected with a string to another block of
mass 3 kg through a smooth pulley as shown below.

6 kg

3 kg

Calculate
(i) the acceleration of the system.
(ii) the tension of the string.

[3.27 ms-2, 19.62 N]

C4, PLO4, MQF LOD 6

b) Two blocks of mass 4 kg and 5 kg are connected with a string through a smooth pulley
as shown in the figure below. The coefficient of friction is the same for both planes,
µ= 0.20.

4 kg

30°
5 kg

(i) Sketch free body diagram for each block. [7.85 N, 8.50 N]
(ii) Calculate the frictional force acting on each block.

C4, PLO4, MQF LOD 6

10. a) An elevator and its load have a combined mass of 800 kg. The elevator is initially
moving downward at 10 ms-1. It slows to a stop with constant acceleration in a distance
of 25 m. What is the tension T in the supporting cable while the elevator is being brought
to rest?
[9448 N]

C4, PLO4, MQF LOD 6

b) A 50 kg woman stands on a bathroom scale while riding in the elevator. What is the
reading on the scale?
(i) when that woman in a descending elevator with acceleration of 2.0 ms-2.
(ii) when that woman in an ascending elevator with acceleration of 3.5 ms-2.

[390.5 N, 665.5 N]


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