Freefall and vertical launch

Multiple Choice

What formula should we use in this question?

• $$𝑣_f=𝑣_i+gt$$  

• $$v_f^2=v_i^2+2gh$$  

• $$h=𝑣_i𝑡+\frac{1}{2}g𝑡^2$$  

Multiple Choice

What formula should we use in this question?

• $$𝑣_f=𝑣_i+g𝑡$$  

• $$v_f^2=v_i^2+2gh$$  

• $$h=𝑣_i𝑡+\frac{1}{2}g𝑡^2$$  

Fill in the Blanks

Multiple Choice

What formula should we use in this question?

• $$𝑣_f=𝑣_i+gt$$  

• $$v_f^2=v_i^2+2gh$$  

• $$h=𝑣_i𝑡+\frac{1}{2}g𝑡^2$$  

• Need more information

Multiple Choice

How do we solve for h using this formula?

$$v_f^2=v_i^2+2gh$$  

• $$h=v_f^2-v_i^2-2g$$

• $$h=\frac{v_f^2-v_i^2}{2g}$$  

• $$h=v_f^2+v_i^2-2g$$  

• $$h=\frac{v_f^2-2g}{v_i^2}$$  

Multiple Choice

When an object is thrown UP, the sign of gravity is...

• POSITIVE

  (velocity is increasing)

• NEGATIVE

  (velocity is decreasing)

Fill in the Blanks

Multiple Choice

How do we solve for t using this formula?

$$𝑣_f=𝑣_i+g𝑡$$  

• $$t=\frac{𝑣_i-𝑣_f}{g}$$

• $$t=\frac{𝑣_f-𝑣_i}{g}$$  

• $$t=\frac{𝑣_f+𝑣_i}{g}$$  

• $$t=𝑣_i+𝑣_f-g$$  

Fill in the Blanks

Fill in the Blanks

Multiple Choice

What's the value of  $$v_i$$  ?

• $$16\ \frac{m}{s}$$  

• $$-16\ \frac{m}{s}$$  

• $$0\ \frac{m}{s}$$  

• Not given

Multiple Choice

When the object thrown up is now coming DOWN, the sign of gravity is...

• POSITIVE

  (velocity is increasing)

• NEGATIVE

  (velocity is decreasing)

Multiple Choice

Gravity is always POSITIVE when the object is falling down

• YES

• NO

• Depends on the problem

Multiple Select

Select all the cases where  $$v_i$$  is equal to 0

• The problem doesn't specify an initial velocity 

• The velocity of an object thrown up before it starts to fall down

• When an object is thrown down

• The velocity of an object thrown up when it reaches the highest point

Poll

When an object is thrown up... does it take the same time to reach the highest point than the time it takes to fall down again?

• Yes

• No