EBK PHYSICS OF EVERYDAY PHENOMENA
EBK PHYSICS OF EVERYDAY PHENOMENA
8th Edition
ISBN: 8220106637050
Author: Griffith
Publisher: YUZU
Question
Book Icon
Chapter 7, Problem 5SP

(a)

To determine

The total momentum of the system prior to the collision.

(a)

Expert Solution
Check Mark

Answer to Problem 5SP

The total momentum of the system prior to the collision is 30,000 kgm/s, south.

Explanation of Solution

Given info: The mass of the car is 1,500kg and its speed is 25 m/s, north. The mass of the truck is 4,500 kg with a speed of 15 m/s, south.

Write the expression for total momentum of the system prior to the collision.

ptotal=ptpc=mtvtmcvc

Here,

ptotal is the total momentum prior to the collision

pt is the momentum of the truck

mt is the mass of the truck

vt is the velocity of the truck

pc is the momentum of the car

mc is the mass of the car

vc is the velocity of the car

Substitute 1500kg for mc,20 m/s, north for vc,4500 kg for mt and 15 m/s, south for vt in the above equation to find ptotal.

ptotal=(4,500kg)(15m/s,south)(1,500kg)(25m/s,north)=30,000kgm/s,south

Conclusion:

Therefore, the total momentum of the system prior to the collision is 30000 kgm/s, south.

(b)

To determine

The velocity of the two vehicles just after the collision.

(b)

Expert Solution
Check Mark

Answer to Problem 5SP

The velocity of the two vehicles just after the collision is 5 m/s south.

Explanation of Solution

Total momentum before collision is equal to the total momentum after collision according to the principle of conservation of momentum.

Write the expression to find the velocity of the two vehicles just after collision.

v=ptotalmt+mc

Substitute 30000 kgm/s, south for ptotal,1500kg for mc and 4500 kg for mt in the above equation to find v.

v=30,000kgm/s,south1,500kg+4,500kg=5m/ssouth

Conclusion:

Therefore the velocity of the two vehicles just after the collision is 5 m/s south.

(c)

To determine

The total kinetic energy of the system before collision.

(c)

Expert Solution
Check Mark

Answer to Problem 5SP

The total kinetic energy of the system before collision is 9.75×105 J.

Explanation of Solution

Write the expression to find the kinetic energy of the system before collision.

KEbefore=KEt+KEc=12mtvt2+12mcvc2

Here,

KEbefore is the total kinetic energy of the system before collision

KEt is the kinetic energy of the truck before collision

KEc is the kinetic energy of the car before collision

Substitute 1500kg for mc,25 m/s, north for vc, 4500 kg for mt and 15 m/s, south for vt in the above equation to find KEbefore.

KEbefore=12(4,500kg)(15 m/s,south)2+12(1,500kg)(25m/s,north)2=9.75×105J

Conclusion:

Therefore the total kinetic energy of the system before collision is 9.75×105 J.

(d)

To determine

The total kinetic energy of the system just after collision.

(d)

Expert Solution
Check Mark

Answer to Problem 5SP

The total kinetic energy of the system just after collision is 7.5×104 J.

Explanation of Solution

Write the expression to find the total kinetic energy of the system just after collision.

KEafter=ptotal22(mt+mc)

Here,

KEafter is the total kinetic energy after collision

Substitute 30,000kgm/s,south for ptotal,1500kg for mc and 4500 kg for mt in the above equation to find KEafter.

KEafter=(30,000kgm/s,south)22(4,500 kg+1,500kg)=7.5×104J

Conclusion:

Therefore, the total kinetic energy of the system just after collision is 7.5×104 J.

(e)

To determine

Whether the collision is elastic.

(e)

Expert Solution
Check Mark

Answer to Problem 5SP

The collision is not elastic.

Explanation of Solution

Elastic collision is associated with no change in the kinetic energy. This implies for an elastic collision to occur, there should be no change in the kinetic energy before and after collision or the kinetic energy should be conserved.

In the given situation the vehicles stick together after collision. The total kinetic energy before collision is 9.75×105 J and that after collision is 7.5×104 J. The difference in the value of the total kinetic energy of the system shows that kinetic energy is not conserved during the head-on-collision. This means that the collision is inelastic.

Conclusion:

Thus, the collision is not elastic.

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Chapter 7 Solutions

EBK PHYSICS OF EVERYDAY PHENOMENA

Ch. 7 - If you catch a baseball or softball with your bare...Ch. 7 - Suppose you move your hand forward to meet the egg...Ch. 7 - A truck and a bicycle are moving side by side with...Ch. 7 - Is the principle of conservation of momentum...Ch. 7 - A ball is accelerated down a fixed inclined plane...Ch. 7 - Two objects collide under conditions where...Ch. 7 - Which of Newtons laws of motion are involved in...Ch. 7 - A compact car and a large truck have a head-on...Ch. 7 - A fullback collides midair and head-on with a...Ch. 7 - Two ice skaters, initially at rest, push off one...Ch. 7 - Two shotguns are identical in every respect...Ch. 7 - When a cannon rigidly mounted on a large boat is...Ch. 7 - Is it possible for a rocket to function in empty...Ch. 7 - Suppose you are standing on a surface that is so...Ch. 7 - Suppose an astronaut in outer space suddenly...Ch. 7 - Suppose that on a perfectly still day, a sailboat...Ch. 7 - A skateboarder jumps on a moving skateboard from...Ch. 7 - A railroad car collides and couples with a second...Ch. 7 - Is the collision in question 28 elastic, partially...Ch. 7 - If momentum is conserved in a collision, does this...Ch. 7 - A ball bounces off a wall with a velocity whose...Ch. 7 - A ball bounces off a wall that is rigidly attached...Ch. 7 - A cue ball strikes an 8 ball of equal mass, which...Ch. 7 - Two lumps of clay traveling through the air in...Ch. 7 - Two lumps of clay, of equal mass, are traveling...Ch. 7 - Two cars of equal mass collide at right angles to...Ch. 7 - A car and a small truck traveling at right angles...Ch. 7 - A cue ball strikes a glancing blow against a...Ch. 7 - Prob. 1ECh. 7 - Prob. 2ECh. 7 - Prob. 3ECh. 7 - Prob. 4ECh. 7 - Prob. 5ECh. 7 - Prob. 6ECh. 7 - Prob. 7ECh. 7 - Prob. 8ECh. 7 - Prob. 9ECh. 7 - Prob. 10ECh. 7 - Prob. 11ECh. 7 - Prob. 12ECh. 7 - Prob. 13ECh. 7 - Prob. 14ECh. 7 - Prob. 16ECh. 7 - For the two vehicles in exercise E16: a. Sketch to...Ch. 7 - Prob. 18ECh. 7 - Refer to example box 7.2 and figures 7.17 and...Ch. 7 - Prob. 1SPCh. 7 - Prob. 2SPCh. 7 - Consider two cases in which the same ball is...Ch. 7 - Prob. 4SPCh. 7 - Prob. 5SP
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