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# HELP! Physical Science questions!!

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48
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I am not sure which formula to use for these. I've tried a few different ways and cannot get the correct answer.

1. If a force of 6.0 N acted on a 0.50-kg block for a distance of 8.0 m, what would be the velocity of the block? (Assume the block is initially at rest.)

2. (a) What is the kinetic energy in joules of a 1080-kg automobile traveling at 96 km/h?

(b) How much work would have to be done to bring a 1080-kg automobile traveling at 96 km/h to a                   stop?

cmoore  Feb 21, 2018
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#1
+12119
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Work = force x distance

6 N x 8 M = 48 N-M

Kinteic enrgy = 1/2 mv^2 = work = 48 N-M       (the m in 1/2 mv^2 is the mass)

= 1/2 (.5 kg) v^2 = 48 N-M

so v= 13.86 M/s

2:    KE =  1/2 1080 kg *( 96 km/hr * 1000m/km * 1hr/3600sec)^2 = 384 kj

(the stuff in red is converting to m/s from km/hr     kj=kilojoule)

The work required to stop the auto is equal to the K.E    384 kj

ElectricPavlov  Feb 21, 2018
edited by ElectricPavlov  Feb 21, 2018
edited by ElectricPavlov  Feb 21, 2018
edited by ElectricPavlov  Feb 21, 2018
edited by ElectricPavlov  Feb 21, 2018
#2
+33
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Thank you!!

cmoore  Feb 22, 2018

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