Danielle is applying 25.2 N to the right on her sled. The sled has a mass of 15.7 kg, and is accelerating across the snow at a rate of 1.35 m/s2.
What is the magnitude of the normal force?
a. 4.00 N
b. 13.57 N
C. 11.63 N
d. 153.86 N

Amachinist needs to remove a tight fitting pin of material a from a hole in a block made of material b. the machinist heats both the pin and the block to the same high temperature and removes the pin easily. what statement relates the coefficient of thermal expansion of material a to that of material b? a) the situation is not possible, heating block b will shrink the hole in the material as the material expands with increasing temperatureb) material b has the same coefficient of expansion as does material ac) material b has a negative coefficient of expansion and a has a positive coefficient of expansiond) material a has a greater coefficient of expansion than does material be) material b has a greate

Africtionless piston-cylinder contains 50 l of saturated liquid r-134a. the piston has a mass and an area resulting in an applied pressure of 500 kpa on the refrigerant. the refrigerant is now heated until its temperature rises to 70∘c. calculate the work (in kj) done during this process.

In an experiment, how can i change human errors? be specific.