Question

A 3-kg ball is projected upward with an initial velocity that makes an angle 85⁰ with the horizontal. The ball follows the path indicated and lands on a shelf 2-m high. How much work did the gravitational force do on the ball? ​

Answer 1

Answer:

gravitational force is working in vertical direction therefore the displacement in vertical direction is taken into consideration but not the range.

so h = u^2sin^Θ/2g

i.e. h = u^2 (0.996)^2/2g

h = u^2 x 0.992016 /20

h = u^2 x 0.049  here h = 2

2/0.049 = u^2

6.3 m/s = u

now the work done = force x displacement

                                  = mg x h

                                  = 3 x 10 x u^2 x 0.049

                                  =  1.47u^2

                                  = 1.47 x 40.8

                                  59.9 or 60 J

                                      or

you can just do mgh = 3 x 10 x 2 = 60 J

Hope this helps love

                                 

Answer 2

Given:

A 3-kg ball is projected upward with an initial velocity that makes an angle 85⁰ with the horizontal. The ball follows the path indicated and lands on a shelf 2-m high.

To find:

Work done by gravity ?

Calculation:

• Always remember that: Gravitational Work is not dependent on the path followed by the object.

• Instead, it is just dependent on the net displacement (i.e. the state or position of the object).

$\therefore \: W_{gravity} = m \times g \times h$

$\implies\: W_{gravity} = 3 \times 10 \times 2$

$\implies\: W_{gravity} =60 \: J$

So, work done by gravity is 60 Joules.