Science chapter 4
. A certain lever has a mechanical advantage of 5.5. How heavy of a load could the lever lift with an input force of 20 N?
110 N
How much work is done lifting a 9.10-kg box straight up onto a shelf that is 1.80 m high?
160 J
Calculate Work Find the work needed to lift a 20-N book 2 m.
20 N x 2 m = 40 J
If the rock has a mas of 1 kg , which is the speed of the rock after it has fallen for 2 s?
20 m/s
A boy and his father went jogging. what is the kinetic energy of the 30 kg boy if he running at 4 m/s
240 j
An input force of 80 N is used to lift an object weighing 240 N with a system of pulleys. What is the mechanical advantage of the pulley system?
3
. A 10 kg box sits on the floor. Approximately how high would you have to lift the box to increase gravitational potential energy by 350 J.
3.5 m
. A person weighing 500 N climbs 3 m. How much power is needed to make the climb in 5 s?
300 N
what is the mass of an object that creates 20,000 joules of energy by traveling 30 m/s
44 kg
Object B has a mass of 10 kg and was lifted at a rate of 3 m/s. What is the kinetic energy of object B.
45 J
What is the potential energy of a 2.5 N book that is placed on a shelf that is 2 meters high.
5 J
According to the graph, which is the best estimate for the kinetic energy from the rocks falling motion after that rock has fallen for 1 s?
50 J
It takes 600 J of work to lift a crate straight up but 1,300 J to push that crate up a ramp to the same height. What is the efficiency of the ramp?
50%
A boy and his father went jogging. what is the kinetic energy of 65 kg father if he is running at m/s
520 j
The long question about rollar blades 2,000 joules 90 kg
7 m/s
what is the velocity of a 150 kg elevator that has 4000 joules of energy.
7 m/s
A machine has an efficiency of 20%. Find the input work of the of the output work is 140 J.
700 J
What is the kinetic energy from the motion of a 0.06 kg tennis ball traveling at a speed of 50 m/s?
75 J
what is the kinetic energy of a 6 kg boat moving at 5 m/s
75 j
Objects A has a mass of 4 kg and was lifted at a speed of 2 m/s . What is the kinetic energy of object A?
8 J
. What is the GPE of an Earth dictionary system if the dictionary has a mass of 5 kg and a distance located 2 m above the ground?
98 J
. Which sequence describes the energy conservations in a car's engine?
Chemical to thermal to mechanical
When a book is moved from a higher shelf to a lower shelf, its ____ changes.
GPE
Which energy transformation is happening in the figure above?
GPE to kinetic energy
Using the scientific definition, which statement is always true of work?
It involves a transfer of energy.
. The muscles of a runner transform chemical potential energy into
Kinetic energy
. What term indicates the number of times a machine multiplies the input force?
Mechanical energy
is the rate at which energy is transformed
Power
The kinetic energy from an object's motion always changes when which factor changes?
The objects speed
Friction causes mechanical energy to be converted into which form?
Thermal energy
Which factor increases as the efficiency of a machine increases?
Work output
A combination of two or more simple machines is a(n)
compound machine
The energy stored in a compressed spring is
elastic potential energy.
Which cannot be done by a machine?
increase work
. According to the__________, the amount of energy still doesn't change.
law of conservation of energy
The ratio of the output force to the input force is the
mechanical advantage
The gravitational potential energy of an object changes when
the object's mass changes