What are two ways friction can be useful

What is the observed frequency of a siren with a frequency of 440 Hz moving towards you at 50 m/s? The speed of sound is 330 m/s.

A 150 kg cart is being accelerated by a tractor at a rate of 5 m/s². How much force is the tractor putting on the cart?

On a day when the temperature reaches 50°F, the temperature in degrees Celsius is: 20°C 10°C 5°C

Suppose that you can lift no more than 650N unaided. How much can you lift using a 1.4m long wheelbarrow that weighs 80N with its CG. 5m from the center of the wheel. The CG of the load in the wheelbarrow is also.

Un vas plin cu lichid cântăreşte 175kg. Ceea ce reprezintă de 5 ori masa vasului gol. Ştiind că volumul interior al vasului este 0,17kl, să se calculeze: a) densitatea lichidului; b) greutatea lichidului.

A spring (k = 790 N/m) has a length of 48 cm when zero net force is applied to it. What will its length be when 230 N of force is applied to stretch it? Question 3 options: 3.4 m 0.77 m 3.9 m 0.29 m

Inert gas used to make bright city lights True or False

A boulder on top of a cliff has a potential energy of 12400J. How high above is the boulder?

If the graph represents speed what is measured on the x and y axes

It is difficult to lift a heavy stone than the lighter one on the earth, why?