1. A loaded tractor-trailer with a total mass of 4.94E+3 kg traveling at 3.48 km

Question

1. A loaded tractor-trailer with a total mass of 4.94E+3 kg traveling at 3.48 km/h coasts into a loading dock and collides, coming to a stop in 0.689 s. What is the magnitude of the average force exerted on the truck by the dock?

2. A 60.5 kg man and his 31.3 kg daughter on skates stand together on a frozen lake. If they push apart and the father has a velocity of 0.744 m/s eastward, what is the magnitude of the velocity of the daughter? (Neglect friction.)

3.To get off a frozen, frictionless lake, a 65.6-kg person takes off a 0.267-kg shoe and thows it horizontally directly away from the shore with a speed of 1.90 m/s.

If the person is 4.35m from the shore, how long does it take for

him to reach it?

4. A 0.264 kg volley ball comes over the net with a horizontal velocity of 2.68 m/s. One of the players on the front line jumps up and hits it back with a horizontal velocity of 8.09 m/s. What was the impulse imparted to the ball?

5.  A car has a mass of 1200 kg and is moving with a speed of 30 m/s.

Its momentum is?

Explanation / Answer

(1)

Use Newton's second law to find force

F = ma

Here, acceleration = final velocity - initial velocity /time

final velocity = 0

initial velocity = 3.48 km/hr = 0.97 m/s

Thereore, the acceleration,

a = 0.97 m/s / 0.689 s = 1.38 m/s2

Now find force

F= ma = 4.94 x103(1.38 m/s2) = 6.84 x103 N

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(2)

Appy conservation of momentum

m(f) v(f) + m(d) v(d)=0

( 60.5 kg ) ( 0.744 m/s ) + ( 31.3 kg ) v(d) = 0

Solve for v(d)

v(d) = 1.43 m/s towards west   

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