Exam of Physics and Chemistry for 4th ESO
Name:
Date:
1. Tom, the cat, is chasing Jerry, the mouse. Jerry runs past Tom at 10.00 m/s. At the same time Jerry
passes Tom, Tom, which was at rest, starts accelerating at 3.00 m/s 2.
a) How long does it take for Tom to catch up with Jerry? (1 point)
b) What is the velocity of Tom when he catches up with Jerry? (0.5 points)
c) If there was a mouse hole located 2.1 meters away from Jerry when Tom began chasing Jerry,
would Jerry make it to the hole without being caught? (0.5 points)
2. The following diagram shows the distance vs time graph for a dog walking along a pavement. Describe
the type of motion and calculate the velocity in each part of the graph.
(1.5 points)
3. Acceleration of gravity on the Moon is 1.67 m∙s-2.
a) Calculate the time taken for a feather to reach the ground if it is dropped from a height of 1.5 m,
as it was carried out by Apollo15 crew. (0.5 points)
b) Compare this time with the time taken on Earth. (0.5 points)
c) If the feather has a mass of 0.5 g, what is its weight on the Moon? Calculate the weight in
Newtons. (0.5 points)
4. Pilar is driving at 90 km∙h-1 and she notices a traffic jam at a distance of 80 m. Calculate the
acceleration required to avoid crushing against the cars. What is the time taken along the motion? (1.5
points)
5. A tractor has two kinds of wheels, whose radiuses are 60 and 130 cm. Assuming that the tractor is
moving at 30 km/h, calculate period and frequency for each wheel and the acceleration at a point placed
at the edge of each type of wheel. (1.5 points)
6. Four forces are applied on a box.
, has a direction South-East, forms an angle of 40º
with the horizontal axis and its length is 10 N,
and
has a direction North-West,
forms an angle of 20º with the horizontal axis and its length is 15 N. Calculate the total force applied on
the box. Express it as a vector using the unit vectors and and calculate its length. (2 points)
Answers
1. Tom, the cat, is chasing Jerry, the mouse. Jerry runs past Tom at 10.00 m/s. At the same time Jerry
passes Tom, Tom, which was at rest, starts accelerating at 3.00 m/s 2.
a) How long does it take for Tom to catch up with Jerry? (1 point)
b) What is the velocity of Tom when he catches up with Jerry? (0.5 points)
c) If there was a mouse hole located 2.1 meters away from Jerry when Tom began chasing Jerry,
would Jerry make it to the hole without being caught? (0.5 points)
Tom won´t catch up with Jerry because
Jerry reaches the mouse hole before Tom catches up with him.
2. The following diagram shows the distance vs time graph for a dog walking along a pavement. Describe
the type of motion and calculate the velocity in each part of the graph.
(1.5 points)
From A to B: Uniform Linear Motion
From B to C: Uniform Linear Motion
From C to D: at rest
From D to E: Uniform Linear Motion
From E to F: Uniform Linear Motion
From F to G: at rest
3. Acceleration of gravity on the Moon is 1.67 m∙s-2.
a) Calculate the time taken for a feather to reach the ground if it is dropped from a height of 1.5 m,
as it was carried out by Apollo15 crew. (0.5 points)
b) Compare this time with the time taken on Earth. (0.5 points)
c) If the feather has a mass of 0.5 g, what is its weight on the Moon? Calculate the weight in
Newtons. (0.5 points)
a)
b)
(it takes less time to reach the ground on the Earth because the acceleration is
bigger)
c)
4. Pilar is driving at 90 km∙h-1 and she notices a traffic jam at a distance of 80 m. Calculate the
acceleration required to avoid crushing against the cars. What is the time taken along the motion? (1.5
points)
→
→
→
→
5. A tractor has two kinds of wheels, whose radiuses are 60 and 130 cm. Assuming that the tractor is
moving at 30 km/h, calculate period and frequency for each wheel and the acceleration at a point placed
at the edge of each type of wheel. (1.5 points)
Wheel 1
Wheel 2
6. Four forces are applied on a box.
,
has a direction South-East, forms an angle of 40º
with the horizontal axis and its length is 10 N,
and
has a direction North-West,
forms an angle of 20º with the horizontal axis and its length is 15 N. Calculate the total force applied on
the box. Express it as a vector using the unit vectors and and calculate its length. (2 points)