Question

Which of the following situations is impossible? An object has velocity directed cast and acceleration directed west. An object has velocity directed cast and acceleration directed east. An object has zero velocity but non-zero acceleration. An object has constant non-zero acceleration and changing velocity. An object has constant non-zero velocity and changing acceleration. An object is thrown upwards with a speed of 16 m/s. How long does it take it to reach a height of 7.0 m on the way up? Neglect air resistance 0.5 s 1.2 s 2.4 s 3.1 s 4.2 s A bullet shot straight up returns to its starting point in 10 s. What is the initial speed of the bullet, assuming negligible air resistance? 9.8 m/s 25 m/s 49 m/s 98 m/s If a vector's components are all negative, then the magnitude of the vector is negative True False

Answer 1

Q6.
Not possible to have a constant non zero velocity & a changing acceleration.
If v were constant, then a would be 0. So, option e.

Q7.
v = 16 m/s
a = g = 9.8 m/s^2
and you want
y = 7.0 m

You can use the equation for vertical displacement: y = vt + 1/2(-g)t^2

Plug in and you get 7.0m = (16m/s)(t) + (1/2)(-9.8m/s^2)(t^2)

so, t = 0.52 s

Q8.
y = Vo t + ½ g t²

0 = Vo (10) + ½ (-9.8) (10)²

Vo = 49 m/s

Q9.
False.