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13 Dec 2019

You and a friend stand on a snow-covered roof. You both throwsnowballs from an elevation of 14 m with the same initial speed of12 m/s, but in different directions. You through your snowballdownward, at 40° below the horizontal; your friend throws hersnowball upward, at 40° above the horizontal. What is the speed ofeach ball when it is 5.0 m above the ground? (Neglect airresistance.)
1. m/s (your snowball)
2. m/s (your friend's snowball)

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Related textbook solutions

Physics: Principles with Applications
7th Edition, 2013
Giancoli
ISBN: 9780321625922

Related questions

In the latest Indian Jones film, Indy is supposed to throw agrenade from his car, which is going 95.0 , to his enemy's car,which is going 125 . The enemy's car is 13.0 in front of the Indy'swhen he lets go of the grenade.

If Indy throws the grenade so its initial velocity relative to himis at an angle of 45 above the horizontal, what should themagnitude of the initial velocity be? The cars are both travelingin the same direction on a level road. You can ignore airresistance.

Hint: The grenade moves in projectile motion, and convert the twovelocities given in the problem from km/hr to m/s. Being anexcellent student of P2, Indy knows that horizontal range of thegrenade must equal the distance that the enemies car is ahead atthe time the grenade is thrown plus the distance the enemies cartravels while the grenade is in the air. This distance is given byv_rel*t, where v_rel the relative velocity of the enemies carrelative to the Indy's and t is the time in the air.

Solve for time that the grenade is in the air in terms ofv_0.

Use the range equation to get the grenade distance as a function ofv_0

Set R=(initial separation)+v_rel*t and get a 2nd order polynomialfor v_0. Use quadratic equation to get v_0. This is the magnitudeof the velocity vector relative to Indy.

and...
Find the magnitude of the velocity relative to the earth.

Hint: Use Galileo's equation where Frame A is ground, Frame B isIndy's car and the object of interest P is the granade.

Use your answer in part A for speed and given direction tocalculate the x and y components of the velocity with respect toIndy's car. The velocity of Indy's car with respect to the groundis straightforward to write in x and y components.

In the latest Indian Jones film, Indy is supposed to throw agrenade from his car, which is going 82.0 km/h, to his enemy's car,which is going 125km/h. The enemy's car is 14.6m in front of theIndy's when he lets go of the grenade.



=====>Part A: What is the Vo ? in km/h

If Indy throws the grenade so its initial velocity relative to himis at an angle of 45 ^\circ above the horizontal, what should themagnitude of the initial velocity be? The cars are both travelingin the same direction on a level road. You can ignore airresistance.

Hint: The grenade moves in projectile motion, and convert the twovelocities given in the problem from km/hr to m/s. Being anexcellent student of P2, Indy knows that horizontal range of thegrenade must equal the distance that the enemies car is ahead atthe time the grenade is thrown plus the distance the enemies cartravels while the grenade is in the air. This distance is given byv_rel*t, where v_rel the relative velocity of the enemies carrelative to the Indy's and t is the time in the air.

Solve for time that the grenade is in the air in terms ofv_0.

Use the range equation to get the grenade distance as a function ofv_0

Set R=(initial separation)+v_rel*t and get a 2nd order polynomialfor v_0. Use quadratic equation to get v_0. This is the magnitudeof the velocity vector relative to Indy.



=====>Part B: What is Vo in km/h?

Find the magnitude of the velocity relative to the earth.

Hint: Use Galileo's equation where Frame A is ground, Frame B isIndy's car and the object of interest P is the granade.

Use your answer in part A for speed and given direction tocalculate the x and y components of the velocity with respect toIndy's car. The velocity of Indy's car with respect to the groundis straightforward to write in x and y components.


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