Andrea, a 65 kg sprinter, starts a race with an acceleration of 1.24 meters/s2.   If she accelerates at that rate for 20.0 meters and then maintains that velocity for the remainder of a 100-meter dash, what will her time (in seconds) be for the race?  In your written solution, provide the force required for the initial acceleration?

In a fit, a toddler throws straight down his favorite 1.5 kg toy with an initial velocity of 2 m/s. What is the magnitude of the change in velocity of the toy from t = 0.14 seconds to t = 0.31 seconds?

A box with mass 32.5 kg rests on a frozen pond, which serves as a frictionless horizontal surface. If a fisherman applies a horizontal force of 14.0N to the box causing it to accelerate to the right. What is the acceleration produced? How far does the crate travel in 10.0 seconds?

Lex Luthor has dropped Lois Lane (initial velocity 0, mass 65.30 kg) from the top of a building of height 385 m. Fortunately, Superman flies to catch her 9.10 m before she hits the ground.  (a) Ignoring air resistance, how fast is Lois moving when Superman catches her? (enter as negative if downwards) (b) What acceleration must Superman give to Lois if he is to stop her before she hits the ground? (enter as negative if downwards)  (c) Not forgetting that Lois also has weight, what force must Superman apply to stop her from hitting? (enter as negative if downwards)

ycla 3. A car travelling at 122 km/h strikes a tree, the front end of the car compresses, and the driver comes to rest after traveling 0.558 m. What was the average acceleration of the driver during the collision? Express your answer in terms of g's (1.00g = 9.80 m/s'). g's %3D Given the fact that humans can withstand a maximum of 25 g's for a short time without brainy injury, what would the condition of this driver most likely be? Impact khl l

Bran is pushing Amira in a sled. The combined mass of the sled and Amira is 40.0 kg. There is a coefficient of kinetic friction between the led and the snow of 0.205. Bran applies a 160 N pushing force at 30.0° below the horizontal. What is Amira's acceleration? (Give your answer in m/s2.)

A semi is traveling down the highway at a velocity of v = 39.5 m/s. The driver observes a wreck ahead, locks his brakes, and begins to slide. The truck has mass m and a coefficient of kinetic friction between the tires and the road of μk = 0.25. Write an expression for the sum of the forces in the x-direction for the truck while braking. Using the results from that input an expression for the trucks acceleration, ax, while braking. What is the magnitude of the acceleration in m/s^2, and how far does the truck travel, d in meters, before stopping?

A lump of clay of mass 0.28 kg is dropped from a height of 10.8 m. The clay comes to a full stop  0.075 s after the moment it first touched the ground. What is the magnitude in newtons of the average force of impact that the clay experienced? Express your answer in two decimal places, with units of Newtons.

A contestant in a winter sports contest pulls a 47 kg brick of ice 25 degrees in the positive horizontal direction with a rope over his shoulders over a frozen lake. Assume the coefficients of static and kinetic friction are µs=0.1 and µk=0.03. 1. Calculate the minimum force F he must exert to get the brick sliding in newtons.  2. What is its acceleration in m/s2 once it starts to move, if that force is maintained?

A car of mass 972 kg is traveling 24.4 m/s when the driver applies the brakes, which lock the wheels. The car skids for 5.27 s in the positive x-direction before coming to rest. a.) What is the car's acceleration (in m/s2)? (Indicate the direction with the sign of your answer.)   (b) What magnitude force (in N) acted on the car during this time?   (c) How far (in m) did the car travel?