Download Exam of Physics and Chemistry, 4 ESO. Name: Date: 1

Exam of Physics and Chemistry, 4th ESO.
Name:
Date:
1. On a horizontal surface a box is pulled by a force of 70 N that forms an angle of 10º
with the floor. The mass of the box is 45 kg and the coefficient of friction with the floor
is 0.13. Calculate:
a) The acceleration the box acquires. (1 point)
b) The space it travels in 7 seconds, if the force is maintained. (0.5 points)
c) The speed the box has after 7 seconds, if the force is maintained. (0.5 points)
2. A box moves with a velocity of 40 m/s on a surface which has a coefficient of friction
of 0.1. This box has a mass of 20 kg. What is the force you need to apply if you want
the box to stop in 10 seconds? (2 points)
3. The maximum speed an Alvia train can take a radius of 400 m without derailing is 80
km/h. This type of train has a mass of 375 tons. Calculate the centripetal force when it
turns with the maximum speed. (1 point)
4. Venus is the second planet from the Sun. It has no natural satellite. It is named after
the Roman goddess of love and beauty. Its period (time it takes to turn one revolution
around the Sun) is 224.7 Earth days and its orbital speed is 35020 m/s. Calculate the
distance between the centers of Venus and the Sun and calculate the angular speed and
the centripetal force of this planet. Data: MSun=1.99∙1030 kg. MVenus=4.87∙1024 kg. (2
points)
5. Mercury is the smallest planet in the Solar System and the one closest to the Sun.
a) Calculate the force of attraction between Mercury and the Sun. (1 point)
b) Calculate the acceleration of gravity in Mercury at a height of 25 km. (1 point)
c) Calculate the orbital speed of Mercury around the Sun and its period. (1 point)
MMercury=3.30∙1023 kg; MSun=1.99∙1030 kg; R Mercury=2440 km; RSun=696342 km; average
distance between the centers of Mercury and the Sun=5.79∙1010 m.
Answers
1. On a horizontal surface a box is pulled by a force of 70 N that forms an angle of 10º
with the floor. The mass of the box is 45 kg and the coefficient of friction with the floor
is 0.13. Calculate:
a) The acceleration the box acquires. (1 point)
b) The space it travels in 7 seconds, if the force is maintained. (0.5 points)
c) The speed the box has after 7 seconds, if the force is maintained. (0.5 points)
seconds.
a) Fx=F∙cos10=70∙cos10º=68.94 N Fy=F∙sin10=70∙sin10º=12.16 N
Y axis
N+Fy -m∙g=0 → N=m∙g-Fy=45∙9.8-12.16=428.84 N
X axis
Ffr=∙N=0.13∙428.84=55.75 N
Fx-Ffr=m∙a →
b)
c) v=v0+a∙t=0+0.29∙7=2.05 m/s
2. A box moves with a velocity of 40 m/s on a surface which has a coefficient of friction
of 0.1. This box has a mass of 20 kg. What is the force you need to apply if you want
the box to stop in 10 seconds? (2 points)
3. The maximum speed an Alvia train can take a radius of 400 m without derailing is 80
km/h. This type of train has a mass of 375 tons. Calculate the centripetal force when it
turns with the maximum speed. (1 point)
4. Venus is the second planet from the Sun. It has no natural satellite. It is named after
the Roman goddess of love and beauty. Its period (time it takes to turn one revolution
around the Sun) is 224.7 Earth days and its orbital speed is 35020 m/s. Calculate the
distance between the centers of Venus and the Sun and calculate the angular speed and
the centripetal force of this planet. Data: MSun=1.99∙1030 kg. MVenus=4.87∙1024 kg. (2
points)
5. Mercury is the smallest planet in the Solar System and the one closest to the Sun.
a) Calculate the force of attraction between Mercury and the Sun. (1 point)
b) Calculate the acceleration of gravity in Mercury at a height of 25 km. (1 point)
c) Calculate the orbital speed of Mercury around the Sun and its period. (1 point)
MMercury=3.30∙1023 kg; MSun=1.99∙1030 kg; R Mercury=2440 km; RSun=696342 km; average
distance between the centers of Mercury and the Sun=5.79∙1010 m.
a)
b)
c)