Question

A 53.0-kg athlete leaps straight up into the air from a trampoline with an initial speed...

A 53.0-kg athlete leaps straight up into the air from a trampoline with an initial speed of 7.5 m/s. The goal of this problem is to find the maximum height she attains and her speed at half maximum height.
a. Select the height at which the athlete's speed is 7.5 m/s as
y = 0. What is her kinetic energy at this point?
What is the gravitational potential energy associated with the athlete?
b. What is her kinetic energy at maximum height?
What is the gravitational potential energy associated with the athlete?
c. Write a general equation for energy conservation in this case and solve for the maximum height. Substitute and obtain a numerical answer.
d. Write a general equation for energy conservation in this case and solve for half the maximum height. Substitute and obtain a numerical answer.

Homework Answers

Answer #1

a)

K.E = 1/2mv2

K.E = 1/2 * 53 * 7.52

K.E = 1490.625 J

and

Gravitational potential energy = 0 J

-----------------

b)

K.E ( max height) = 0 J

Gravitational potential energy = 1490.625 J

--------------------------

c)

1/2mv12 + mgy1 = 1/2mv22 + mgy2

y2 = y1 + (( v12 - v22 ) / 2g )

y2 = 0 + ((7.52 - 0) / 2 * 9.8)

y2 = 2.87 m

----------------------------------------------------

(d)

just use kinematics

v2 = sqrt ( v12 + 2g ( y1 - y2))

v2 = sqrt ( 7.52 -  2 * 9.8 * 0.5 *2.87)

v2 = 5.3 m/s

Know the answer?
Your Answer:

Post as a guest

Your Name:

What's your source?

Earn Coins

Coins can be redeemed for fabulous gifts.

Not the answer you're looking for?
Ask your own homework help question
Similar Questions
A 66.5-kg athlete leaps straight up into the air from a trampoline with an initial speed...
A 66.5-kg athlete leaps straight up into the air from a trampoline with an initial speed of 7.8 m/s. The goal of this problem is to find the maximum height she attains and her speed at half maximum height. a. What are the interacting objects and how do they interact? b. Select the height at which the athlete's speed is 7.8 m/s as y = 0. What is her kinetic energy at this point? What is the gravitational potential energy...
3. A 67 kg trampolinist leaves the trampoline in the vertical direction with a velocity of...
3. A 67 kg trampolinist leaves the trampoline in the vertical direction with a velocity of 7 m/s. a) What is the athlete’s maximum kinetic energy? _________________ b) What is the athlete’s maximum potential gravitational energy? _________________ c) Plot (on the same graph) the athlete’s potential and kinetic energy versus time for the entire duration that the athlete is in the air. On the plot, label the following phases on the graph: take-off, top of jump, and landing. Also label...
A child is bouncing an a trampoline. The child has a mass of 50.5 kg ....
A child is bouncing an a trampoline. The child has a mass of 50.5 kg . She leaves the surface of the trampoline with an initial upwards velocity of 10.2 m/s . When she reaches height 1.60 m above the trampoline (still on the way up), she grabs a large (stationary) plastic block. The mass of the block is 8.00 kg . (Figure 1) For this problem, use g=9.80 meters per second per second for the magnitude of the acceleration...
A 1.90 kg water balloon is shot straight up with an initial speed of 3.20 m/s....
A 1.90 kg water balloon is shot straight up with an initial speed of 3.20 m/s. (a) What is the kinetic energy of the balloon just as it is launched? (b) How much work does the gravitational force do on the balloon during the balloon's full ascent? (c) What is the change in the gravitational potential energy of the balloon–Earth system during the full ascent? (d) If the gravitational potential energy is taken to be zero at the launch point,...
A 9.8 kg cannonball was fired from a cannon straight up with an initial velocity of...
A 9.8 kg cannonball was fired from a cannon straight up with an initial velocity of 42 m/s. (A) Assuming that all its initial kinetic energy was transformed into gravitational energy, what is the maximum height that the cannonball could reach? (B) Suppose that 20% of its initial kinetic energy was lost due to friction with the air (air resistance). What is the maximum height that the cannonball could now reach? (C) How long will it take, after the cannon...
A man of mass m1 = 64.5 kg is skating at v1 = 7.60 m/s behind...
A man of mass m1 = 64.5 kg is skating at v1 = 7.60 m/s behind his wife of mass m2 = 53.0 kg, who is skating at v2 = 3.80 m/s. Instead of passing her, he inadvertently collides with her. He grabs her around the waist, and they maintain their balance. (a) Sketch the problem with before-and-after diagrams, representing the skaters as blocks. (b) Is the collision best described as elastic, inelastic, or perfectly inelastic? elastic inelastic perfectly inelastic...
A 20 kg kid jumps from a moving swing. When she leaves the swing she is...
A 20 kg kid jumps from a moving swing. When she leaves the swing she is y1=1.0 m above the ground, moving with a speed v1=2 m/s at an angle 60 degrees above horizontal. (a) What is the change in potential energy (∆U) as she moves from the swing to the ground (y =0 m)? (b) Use conservation of mechanical energy (∆K + ∆U = 0) to find her speed as she reaches the ground. (c) What is the change...
A 20 kg kid jumps from a moving swing. When she leaves the swing she is...
A 20 kg kid jumps from a moving swing. When she leaves the swing she is y1 “ 1.0 m above the ground, moving with a speed v1 “ 2 m{s at an angle 60 ̋ above horizontal. (a) What is the change in potential energy (∆U ) as she moves from the swing to the ground (y “ 0 m)? (2 pts) (b) Use conservation of mechanical energy (∆K ` ∆U “ 0) to find her speed as she...
A 41.0-kg skier with an initial speed of 1.5 X 101 m/s coasts up a 2.50-m-high...
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...
Question 1 (1 point) Which is not necessary in order to do work on an object...
Question 1 (1 point) Which is not necessary in order to do work on an object (use the scientific definition of work)? Question 1 options: There must be a change in momentum. A net force must be applied to the object. The object must undergo a displacement. A component of the force must be in the direction of motion. Question 2 (1 point) The change in gravitational potential energy for a 1.9 kg box lifted 2.2 m is: Question 2...
ADVERTISEMENT
Need Online Homework Help?

Get Answers For Free
Most questions answered within 1 hours.

Ask a Question
ADVERTISEMENT