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A child throws a 0.50 kg snowball at his friend at 12.0 m/s but the snowball lands on the ground in front of his friend.
The snowball is 1.3 m above the ground when it leaves the child’s hand.
(a) What is the (i) kinetic energy & (ii) potential energy of the snowball at the time of release?
(b) What is the total energy of the snowball (i) at the time of release & (ii) just before it hits the ground?
(c) What is the snowball’s kinetic energy just before it hits the ground in front of his friend?
(d) How fast is the snowball moving just before it hits the ground in front of his friend?
A toboggan carrying two children (total mass = 85 kg) reaches its maximum speed at the bottom of a hill, and then glides to a stop in 21 m along a horizontal surface.The coefficient of kinetic friction between the toboggan and the snowy surface is 0.11.
(a) Draw a FBD of the toboggan as it slows down, and calculate the magnitude of ALL the forces in the diagram.
(b) Calculate the acceleration of the toboggan.
(c) Calculate the work done on the toboggan by the friction on the snowy surface.Should the work be positive or negative?Explain.
10. A pulley system operated with an electric motor consumes 5.0 kJ of energy as it does 3.2 kJ of work in raising an object. The efficiency of this technology is:
(a) 64% (b) 84%
(c) 119% (d) 156%
8. Consider an object falling from a height of 300 m. If we ignore air resistance, its total energy:
(a) increases during the fall.
(b) decreases during the fall.
(c) remains constant during the fall.
(d) is zero at the start of the fall.
7. In which of the following is gravitational potential energy being transformed into kinetic energy?
(a) A car accelerating on a level road.
(b) A raindrop falling freely through the air.
(c) Water turning an electric turbine.
(d) A stone thrown up into the air.
6. If the mass of an object is quadrupled and the speed decreased by a factor of three, by what factor does the kinetic energy change?
(a) 4/3 (b) 16/3
(c) 4/9 (d) 16/9
9. A 6.0 kg object (at rest) is released from a height of 80 m. If air resistance is negligible and g = 9.8 N/kg, the kinetic energy of the mass when it is 20 m above the ground is:
(a) 4.7 × 103 J (b) 3.5 × 103 J
(c) 2.4 × 103 J (d) 1.2 × 103 J
Create a public class named: Employee that would get the firstname and lastname of each
employee from the keyboard/user
Assume we observe that the equilibrium price of a certain good has DECREASED significantly over the past 5 years, with virtually NO CHANGE in the equilibrium quantity. Which of the following is the most likely explanation? Over the past 5 years:
1.both supply and demand have decreased.
2.demand has increased but supply has decreased.
3.both supply and demand have increased.
4.supply has increased but demand has decreased.
The weights of students in a certain school are normally distributed with a mean weight of 66 kg. 10% have a weight greater than 70kg. What percentage of students weighs between 62kg and 66kg?
#339914 on Dec 2023