PHys 1050 Page 4 of 5 Q3 A A 1.5 kg object is displaced from an initial position

Question

PHys 1050 Page 4 of 5 Q3 A A 1.5 kg object is displaced from an initial position to a fina position where (-1.00 +2.50 m r, (3.00 i 1.50 3)m During the displacement, a force F- 0 i +8001) N acts on the objects i. calculate the work done by the force F ii. The y-axis is the vertical direction. What is the work done by gravity? iii. If the object begins at rest, determine the snal speed of the object. B. A 200 kg object on a smooth, level, frictionless table has a velocity of (0.5 i 20 j) m/s. An external force F then acts on the object for 4.0 s. The x-axis and y-axis are parallel with the surface. longer applied, the velocity is (.5i-2.0 m/s After the force is no Determine the change in linear momentum of the object. ii. Calculate the average external force acting on the object.

Explanation / Answer

Here

3)

r1 = -1 i + 2.5 j

r2 = 3 i + 1.50 j

net displacement , r = r2 - r1

r = 3 i + 1.50 j -( -1 i + 2.5 j)

r = 4 i - 1 j m

i) work done by F = r .F

work done by F = (4 i - j).(10 i + 8 j)

work done by F = 40 - 8

work done by F = 32 J

ii)

work done by gravity = - 1.5 * 9.8 j .(4 i - j)

work done by gravity = 14.7 J

iii)

let the final speed if v

Using work energy theorum

0.5 * 1.5 * v^2 = 14.7 + 32

v = 7.9 m/s

the final speed of object is 7.9 m/s

B)
v = 0.5 i - 2 j m/s

t = 4 s

i)

change in linear momentum = m * (vf - vi)

change in linear momentum = 2 * (1.5 i - 2 j - (0.5 i - 2 j))
change in linear momentum = 2 * (1 ) i

change in linear momentum = 2 i Kg.m/s

please post rest in a seperate question

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