Question

A 57.8-kg skateboarder starts out with a speed of 1.98 m/s. He does 82.3 J of work on himself by pushing with his feet against the ground. In addition, friction does -232 J of work on him. In both cases, the forces doing the work are non-conservative. The final speed of the skateboarder is 8.47 m/s. (a) Calculate the change (PEf - PE0) in the gravitational potential energy. (b) How much has the vertical height of the skater changed? Give the absolute value.

Answer #1

here,

the mass of skateboarder , m = 57.8 kg

the initial velocity , u = 1.98 m/s

the work done by him , W1 = 82.3 J

the work done by friction , Wff = - 232 J

final velocity , v = 8.47 m/s

using Work energy theorm

W1 + Wff + Wg = 0.5 * m * ( v^2 - u^2)

82.3 - 232 + (- dUg) = 0.5 * 57.8 * (8.47^2 - 1.98^2)

dUg = - 2110 J

the change in gravitational potential energy is - 2110 J

b)

the vertical height of the skater changed , h = dUg /(m * g)

h = - 2110 /(57.8 * 9.81) m

h = - 3.72 m

A 51.8-kg skateboarder starts out with a speed of 2.28 m/s. He
does 105 J of work on himself by pushing with his feet against the
ground. In addition, friction does -251 J of work on him. In both
cases, the forces doing the work are non-conservative. The final
speed of the skateboarder is 6.36 m/s. (a) Calculate the change
(PEf - PE0) in the gravitational potential energy. (b) How much has
the vertical height of the skater changed? Give...

A 61.5-kg skateboarder starts out with a speed of 1.71 m/s. He
does 105 J of work on himself by pushing with his feet against the
ground. In addition, friction does -298 J of work on him. In both
cases, the forces doing the work are non-conservative. The final
speed of the skateboarder is 5.93 m/s. (a) Calculate the change
(PEf - PE0) in the gravitational potential energy. (b) How much has
the vertical height of the skater changed? Give...

A 63.3-kg skateboarder starts out with a speed of 1.67 m/s. He
does 81.1 J of work on himself by pushing with his feet against the
ground. In addition, friction does -280 J of work on him. In both
cases, the forces doing the work are non-conservative. The final
speed of the skateboarder is 6.37 m/s. (a) Calculate the change
(PEf - PE0) in the gravitational potential energy. (b) How much has
the vertical height of the skater changed? Give...

A skateboarder starts up a 1.0-m-high, 30∘ ramp at a speed of
5.2 m/s . The skateboard wheels roll without friction. At the top,
she leaves the ramp and sails through the air.
Part A
How far from the end of the ramp does the skateboarder touch
down?

A skateboarder starts up a 1.0-m-high, 30? ramp at a speed of
7.2 m/s . The skateboard wheels roll without friction. At the top,
she leaves the ramp and sails through the air.
How far from the end of the ramp does the skateboarder touch
down?
Express your answer to two significant figures and include the
appropriate units.

3) A 3 kg block is sliding at an initial speed of 9 m/s across a
surface, encountering a constant friction force of 10 N. How much
work is done on the block after it slides 25 cm? Correct, computer
gets: -2.50 J Hint: Does the block gain or lose energy during this
process? What sign does this imply for the work done on it? 4) How
fast is the block moving after sliding 25 cm? Correct, computer
gets: 8.91...

A 41.0-kg skier with an initial speed of 1.5 X 101 m/s coasts up
a 2.50-m-high rise as shown below. The coefficient of friction
between her skis and the snow is 0.0800. a) Where do you define the
gravitational potential energy Ug to equal 0 J? b) If the skier has
energy at the bottom of the hill state what kind it is and
determine its value. c) If the skier reaches the top of the hill
what kind of...

ADVERTISEMENT

Get Answers For Free

Most questions answered within 1 hours.

ADVERTISEMENT

asked 2 minutes ago

asked 3 minutes ago

asked 7 minutes ago

asked 26 minutes ago

asked 36 minutes ago

asked 55 minutes ago

asked 1 hour ago

asked 1 hour ago

asked 1 hour ago

asked 2 hours ago

asked 2 hours ago

asked 2 hours ago