physics

posted by .

A 4.20-kg watermelon is dropped from rest from the roof of a 28.0-m -tall building and feels no appreciable air resistance. Calculate the work done by gravity on the watermelon during its displacement from the roof to the ground. Just before it strikes the ground, what is the watermelon's kinetic energy? Just before it strikes the ground, what is the watermelon's speed? Would the answer in part A be different if there were appreciable air resistance? Would the answer in part B be different if there were appreciable air resistance? Would the answer in part C be different if there were appreciable air resistance?

• physics -

(a)W(gravity) = mgh

(b) mgh =mv²/2
v=sqrt(2gh)
(c) the same
(d)
mgh = W(fr) + mv1²/2
v1 <v

• physics -

(d) Just before it strikes the ground, what is the watermelon's speed?

Vterminal = sqrt(2*acceleration*displacement) = sqrt(2*9.8 m/s^2*20 m) = 19.80 m/s

Respond to this Question

 First Name School Subject Your Answer

Similar Questions

1. Physics

My midterm is tomorrow and I have a couple questions that I need to study. Ive tried and tried and cannot figure these out. 1) A ball is dropped from a roof and takes 3.0s to reach the ground. Calculate the elevation of the roof above …
2. physics

4.80-kg watermelon is dropped (zero initial speed) from the roof of a 25.0-m-tall building. a) Calculate the work done by gravity on the watermelon during its displacement from the roof to the ground. b) What is the kinetic energy …
3. physics

A brick is released with no initial speed from the roof of a building and strikes the ground in 1.50 {s}, encountering no appreciable air drag. A. How tall, in meters, is the building?
4. physics

A brick is released with no initial speed from the roof of a building and strikes the ground in 1.50 {s}, encountering no appreciable air drag. A. How tall, in meters, is the building?
5. physics

the largest watermelon ever grown had a mass of 118 kg. suppose this watermelon were exhibited on a platform 5 m above the ground . after the exhibition, the watermelon is allowed to slide along to the ground along a smooth ramp, How …
6. physics

A watermelon cannon fires a watermelon vertically up into the air at a velocity of + 9.50 m/s, starting from an initial position 1.20 meters above the ground. When the watermelon reaches the peak of its flight, what is the elapsed …
7. Physics

A watermelon cannon fires a watermelon vertically up into the air at a velocity of +11.5 m/s, starting from an initial position 1.20 meters above the ground. When the watermelon reaches the peak of its flight, what is (a) its velocity, …
8. physics

A large building has an inclined roof. The length of the roof is 69.5 m and the angle of the roof is 18.0° below horizontal. A worker on the roof lets go of a hammer from the peak of the roof. Starting from rest, it slides down the …
9. Physics

A target lies flat on the ground 4 m from the side of a building that is 10 m tall, as shown below. The acceleration of gravity is 10 m/s2 . Air resistance is negligible. A student rolls a 4 kg ball off the horizontal roof of the building …
10. physics

David Wetterman drops a 5 kg watermelon from the top of a 30 m building. What is the velocity of the watermelon as it smashes into the ground (neglecting air resistance)?

More Similar Questions