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PHY101
Test 1
Name: _____________________________
Date: ______________
Total points: 50
Show detailed calculations to receive full points. Use proper units. If your work is not legible it
will NOT be graded.
1. (A) (1 point) Define a vector quantity?
B) (1 point) Which of the following is a vector (pl. indicate by circling the word)?
i) Velocity, ii) mass, iii) object moving with constant speed in a circular path, iv) work, v) weight
and vi) momentum.
C) (2 point) If a ball is tossed straight up with a velocity of 5 m/s, what is its velocity and
acceleration at the top of its path?
D) (4 point) A rock is dropped from the top of a tower 50 m high.
i) How long does it take to reach the ground?
ii) What is the velocity of the rock when it touches the ground?
Dr. Soma Dey
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PHY101
Test 1
2. (6 points)Fill in the blanks with (exact technical) appropriate words to define the three laws of
Newton.
A) Newton’s ___________ law: The acceleration of an object is _________ proportional to the
_________________ acting on the object, and is inversely proportional to the ___________
of the object.
B) Every object continues in a state of rest or of _____________ _____________ in a straight
line unless acted on by a _______________ __________ ________________. This law is
also known as the law of ____________________.
C) Whenever one object exerts a force on a second object, the second object exerts an equal
and _________________________ force on the first. These two forces are effective only
during an interaction between two objects and are known as the __________________ and
____________ forces.
3. (3 + 2 + 1 point)Determine the acceleration of a 20 kg box if a boy pulls it steadily with a force of
120 N and the friction force acting on the box is 110 N? Draw a neatly labeled force diagram.
Which principle/ law is used to solve this problem.
4. (1 + 4 + 2 point) What is the effect of impulse on an object? Leroy, who has a mass of 100 kg, is
skateboarding at 9.0 m/s when he smacks into a brick wall and comes to a dead stop in 0.2 s. i)
Find the deceleration of the object. ii) Find the force of impact?
Dr. Soma Dey
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PHY101
Test 1
5. (2 point) What is the law of conservation of momentum? Under what condition is it valid?
6. (1+ 5 point)A giant frog of mass 2.0 kg is placed on a skateboard of mass 3.0 kg which is at rest.
When the frog jumps horizontally in a forward direction from the skateboard, the skateboard rolls
backward (recoils) at a speed of 1.4 m/s. Which principle would you use to solve the problem?
Calculate the frog’s horizontal jumping speed and indicate the direction too.
7. (1 + 2 + 4 point)What is the kind of energy possessed by an object in motion? State the law of
conservation of energy? A rollercoaster car with mass 150 kg starts from rest at a height of 10 m
on a frictionless rollercoaster. Calculate the speed of the car when its height is 5 m?
Dr. Soma Dey
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PHY101
Test 1
8. (2 + 4 point)A toy car of mass 1500 kg has a motor that can supply it with power 100 Watts. Find
the work done by the engine after running for 5 sec? Using the work-energy relationship find the
velocity of the car after 5 sec?
9. (3 + 3 point)Jenna leans over the edge of a cliff of height 33 m and projects a rock horizontally at
12 m/s. How long is the rock in the air before it hits the ground? Calculate how far from the base
of the cliff the rock lands?
Formulae sheet:
F = 0
Acceleration = change in velocity/ time interval
In free fall: V= gt
Weight = mg
Momentum = mv
Work = force x distance
Potential energy = m g h
Dr. Soma Dey
Speed = distance / time
In free fall: D = (0.5) g (t^2)
Force = ma
Impulse = Ft
Power = work / time
Kinetic energy = (0.5) m (v^2)
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