A hot air balloon weighing 30N is tied to the ground by astring to prevent from floating off the ground. The volume of the balloon is 20m and the density of air is 1.3kg. what is the upthrust acting on the balloon take g=10ms and whats the force exercted by the rope on the balloon?

One day, after pulling down your window shade, you notice that sunlight is passing through a pinhole in the shade and making a small patch of light on the far wall. you see that the patch of light seems to be a circular diffraction pattern. it appears that the central maximum is about 1 cm across and you estimate that the distance from the window shade to the wall is about 3 m. what is (a) the average wavelength of sunlight? (b) the diameter of the pinhole?

The law of conservation of energy states that energy cannot be created or , energy can be from one substance to another. the first blank is ' destroyed ' and for the second blank is ' transferred '

Aparticle initially moving east with a speed of 20.0 m/s, experiences an acceleration of 3.95 m/s, north for a time of 8.00 s. what was the speed of the particle after this acceleration, in units of m/s? give the answer as a positive number.