Fundamentals of Applied Physics (GSDR2115)
Higher Institute of Transport and Logistics (HITL)
Semester: First Semester
Level: 200
Year: 2016
Page 1 of 2
Exercise 1: Effects of rebounding and crumpling vehicles and safety.
A car with a mass (m
1
= 6000
kg)
moving with the velocity
V
1
= 120
km/ h
collides with another car having a mass (m
2
=
12500kg) and velocity V
2
= 60km/h. The two cars are moving : straight line road in reverse
sense. After the frontal collision, two cases can be examined as shown in the figure
1. Select the case which corresponds to: conservation of kinetic energy?
2. Elastic collision?
3. The conservation of kinetic energy?
4. inelastic collision?
5. Give the expression of momentum and kinetic energy before each collision.
6. Let us consider the case (A):
6.1) Give the expression of momentum and kinetic energy after the collision
6.2) Give the expression of the velocities V1 and V2 after collision
6.3) Calculate the force created on drivers (1) and (2) with respective masses m
1
=80kg and m
2
=
70kg, after collision if this collision happened in 2 seconds, after collision i: this
collision happened in 2 seconds,
7. Let us consider the case (B):
7.1) Give the expression of momentum and kinetic energy after the collision
7.2) Give the expression of the velocities V after collision
7.3) Calculate the force created on drivers (1) and (2) with respective masses m
1
=80kg and m
2
=
70kg, after collision if this collision happened in 2 seconds.
8) During collision, do occupants of automobiles certainly prefer small forces or great forces upon
their bodies?
THE UNIVERSITY OF BAMENDA UNIVERSITE DE BAMENDA
HIGHER INSTITUTE OF TRANSPORT AND INSTITU DE TRANSPORT ET
LOGISTIQUE
LOGISTICS (I.S.T.L)
School: H.I.T.L Department: General Studies Lecturers(S): Dr. DADA Jean-Pierre
Course Code: TL1110 Course Title: Fundamentals of applied physics OPTIONS: LT, TL, MT and CU
Date: …….., 2016 HALL:………… Time: 2hours NATURE: EXAM
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Page 2 of 2
9) The importance of rebounding is critical for automobile accidents. From cases (A) and (
B
)
9.1)
What is the safer case for the driver (1)
9.2)
What is the safer case for the driver (2)
9.3)
What is the worst case for the driver (1)
9.4) What is the worst case for the driver (2)
9.5) What hare automobile designers using to protect passengers when there is collision?
(List two examples).
9.6) In car collision, do you think that the mass of die driver can be a parameter of safety?
What do you prefer between a fat driver and a tinny driver as safety is concerned after collision?
10) Some automobiles have crumpled zones or sections in cars which are designed to crumple up
when the car encounters a collision. Answer by YES or NO:
10.1)
By crumpling, the car is less likely to rebound upon impact -s
10.2)
By crumpling, the momentum changes and the impulse is minimized.
10.3)
The crumpling of the car lengthens the time over which the car's momentum is changed
10.4)
By crumpling, the time of the collision is increasing
10.5)
By crumpling, the force of the collision is greatly reduced.
10.6) By crumpling, the time of the collision is reducing
10.7) By crumpling, the force of the collision is greatly increased.
11) According to this exercise, answer by Yes or No:
11.1)
Crumpling a vehicle helps to protect the driver dur.ng accident
11.2)
Crumpling a vehicle helps to protect the vehicle during accident
11.3)
Not crumpling a vehicle helps to protect the driver during accident
11.4)
Not crumpling a vehicle helps to protect the vehicle during accident
Exercise2: Equilibrium
To move heavy boxes A
i
(i = 1,2,…,6) with the mass m
i
(i =
1,2,…6), from a boat, one uses the figure below. A long rod DB
is able to rotate U the point O around (∆) axis. It contains a heavy
solid fixed at the point B and having the fix weight
. The
distance between the box A
t
and (∆) axis is called ℓ
. A small cable (with negligible mass), fixed at
the variable point A, can support one box A
i
(i = 1,2,…,6) (see figure). By varying the distance x, it
is possible to move one box from the boat, turn horizontally at put the box on the ground (see
figure).
1) List all forces applied to each element of the entire system, particularly, the cable AA
1
(3 marks)
2) By applying equilibrium condition to the system, find the relation between x, m
i
, ℓ
. and
other data
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